In outer space on the planet called The Salt Lick, ponies are partying all around, including Party Horse 42699. A female horse taps him and points to the exit. Outside the club, She gives him her necklace, waves him goodbye and leaves. Party Horse 42699 fell on his legs.

~Time Skip~

"We did it, dudes! We mowed the entire lawn without taking a single break! You wanna go get some lunch?" Mordecai asked. "Yeah, sure." (Y/n) said. "Aw yea-uh, I do! Nothing on Earth's gonna stop us from getting some lunch! Huh?" They see a spacecraft falling out of the sky and lands on the lawn, creating a big hole. "Party Horse!" They walk towards it as they chant. "Party, party, party, party, party, par..." the spacecraft opens. "Huh?" The trio asked. Party Horse 42699 sniffles. "Oh, Chrissy!" He cries. Later at the house, he is lying on the couch, and (Y/n), Mordecai and Rigby are standing there. "UUUUUUGGGHHH!" He cried. "Dude, what happened to you?" Mordecai asked. "Are you okay?" (Y/n) asked softly.

"Chrissy happened, man, she dumped me, and she'll probably never talk to me again." He replied. "That's rough." (Y/n) said. "What went wrong?" Rigby asked. "Augh! It's all her dad's fault. He's always telling her my partying is "compulsive" and that I'm a "danger to myself and others." I tried to talk to my bros on Party Horse Planet for advice, but they just duct taped me to a flagpole and put my underwear down. After that, I came to Earth hoping you dudes can help me." Party Horse 42699 said. "Wooooaaaaahhhh..." the trio said. "Uh, don't worry, dude, we'll help you get your girlfriend back." Mordecai said. "You will?" Party Horse 42699 asked.

"It's easy, you just gotta get something nice to show her you care about her." (Y/n) said. "Yeah, man, the mall has like 20 stores that only sells stuff for guys who need to apologize to their girlfriends. With our help, you'll be back in the saddle in no time." Rigby agreed. "Dude, saddle jokes, not cool." Later at the mall, Party Horse 42699 is partying in a dress store with a disco ball, in a sunscreen store with two bottles of sunscreen, and in a clothes store with three purses and in a pet store with a bird. Later they're in the spacecraft in the hole.

Party Horse 42699 is carrying flowers, a box of chocolates and jewelry. "Thanks a lot for your help, guys. Sorry you can't ever go back to that mall again." He said. "Eh, you only ruined like seven stores with your partying." Rigby said. "Good luck, man. Let us know how it goes." (Y/n) said. "Oh, you know I will!" He gets into his spacecraft and leaves as (Y/n), Mordecai and Rigby cough. "Chrissy's gonna love those presents." Rigby said. "Yeah, you can't go wrong with jewelry, flowers and chocolate, every guy knows that." Mordecai said. They look around the hole. "Benson's gonna be really mad about this hole." Rigby said, and (Y/n) sighs. "I'll get the shovels." She said.

8 Hours Later

They finished digging up the hole. "And done." (Y/n) said. " Phew! Now like I was saying before about lunch, nothing on Earth is gonna..." Rigby said. The spacecraft comes back, creating another big hole as Mordecai and Rigby scream; the spacecraft opens, confetti shoots out and Party Horse 42699 comes out. "Okay... you REALLY gotta stop saying that." (Y/n) said. "Dudes! Chrissy did not like the presents!" Party Horse 42699 shouted. "But every guy knows you can't go wrong with jewelry, flowers and chocolate." Mordecai said. "I repeat, the presents were a major fail. She said that stuff is what guys think girls want and all those presents did was prove I was thinking about some generic idea of a girl, and not her specifically." Party Horse 42699 said.

"Whoa..."  Mordecai said. "That's so complicated." Rigby said. "After Chrissy negged on your prezzos, I panicked and made her a mixtape of dope party jams called "Bass in Your Face,"  and for some reason, that was a bust, too." Party Horse 42699 said. "But that sounds like a really good mix." Mordecai said. "Uh-nuh, duh! Augh!" Party Horse 42699. "Sorry, buddy. I guess we need a female prospective if we're gotta crack this nut you call Chrissy. (Y/n)?" Rigby asked, turning to her.

"Have you've tried talking to her, just being real?" She asked. "Real?! I'm the realist there is! Check this out." He starts partying. "BOOM!! That's real." Party Horse 42699 said. "Um, let's try some role playing, maybe?" (Y/n) asked. "Okay." He said. "I'll be Chrissy, Party Horse, you be you, and go." (Y/n) said. "Don't do me like this, Chrissy, we're a perfect match! With that body and these abbs, we're the hottest couple on Party Horse Planet." He said.

"First of all, wow, but you could focus on something besides her looks?" (Y/n) asked. "Hmm, well, she dedicates herself to her interest, I think that's cool, and I like that she's into art." Party Horse 42699 said. "Good, this is good." (Y/n) said. "And I guess there's the way she elevates my very being and makes me wanna be a better person." Party Horse 42699 said. "Party Horse, that was perfect. Call Chrissy and tell her exactly what you just said." (Y/n) said. "Or you could cry like Mordecai did after Anna—" Mordecai punches Rigby in the arm. "OW!!!!" (Y/n) snickers. "Thanks, guys. I'm gonna call her." Party Horse 42699 pulls up a ball-like holographic phone, dials Chrissy and calls her. "Chrissy!" He shouted.

"Party Horse, I'm sorry, but..." she began. "Wait. I-I have something I need to say. Chrissy, I think you're really cool and your art skills, they-they always amaze me. You're like the Picasso of drawing gross stuff on sleeping dudes' faces. Just give me one chance to prove that partying doesn't control me. Let me take you out on a nice quiet dinner tonight. No base drops, no heinous property damage, just you, and me, and our thoughts." Party Horse 42699 said. "That's actually a really nice idea." She replied. "It is?" Party Horse 42699 asked. "Okay, Party Horse, one date. Tonight. Last chance." Chrissy said. "Yes! You won't regret this!" A call from another Party Horse named Charlie calls. "Oop. Call waiting. One sec, babe." He calls Charlie. "Brah, lumberjack party tonight at Chad's pad. Rashad, Brad, and Tad are going in matching plaid." Charlie said.

"Dude, that sounds rad! I'm in!" Charlie's call ended and he's back on Chrissy's call. "Chrissy, I know I said no more parties tonight, but there's a party tonight!" He said. "You blew it, Party Horse. Goodbye." She hangs up. "Huh?" Another incoming call occurs. "Oh, phew! Chrissy, I thought y—" Principal Party Horse calls him. "Principal Party Horse?!" He asked. "I told you to stay away from my daughter! If I see you again, you're glue!" His call ends. "That guy really doesn't like you, huh?" (Y/n) asked. "Awww! Augh!" He collapsed on the couch. "It's not fair! I didn't ask to be born this way. If only there was some way to exhaust this burning party star inside of me." He said.

Mordecai gasps. "That's it, dude! We gotta party the party out of you and then you can get Chrissy back." He said. "Aw, yeah! You gotta party so crazy you never wanna party again." Rigby said. Party Horse 42699 gasps. "We're going to Party Horse Planet!" He shouted. "WHOOOOO!!!!" Party Horse 42699 crashes through the park house door as they are going to Party Horse Planet. In outer space, the spacecraft lands on Party Horse Planet, creating a hole, then Party Horse 42699, (Y/n), Mordecai and Rigby come out. "So these pods really don't have a way to land safely?" (Y/n) asked.

"Nah, all the scientists are too busy partying to figure it out." He pulls out a Party Horse brochure and shows them the map. "Okay, here on Party Horse Planet, there's a party on every block. You'll see that party houses are indicated on the map by a party hat. The way I figured it, we're gonna hit them all tonight if there's any hope of partying my party out." He said. "Wow, you're so well-prepared when it comes to parties." Mordecai said. "And you're surprised?" (Y/n) asked. "Oh, this is just the local news paper. I actually have terrible spatial skills, so let's just start here." They come to the first party house, Party Horse 42699 knocks on the door and the Colonial Party Horse answers it.

"Dudes, welcome to the Colonial America Party! Come inside and get your Delaware on!" Colonial Party Horse said. "WHOOOOOOO!!!!!!!" They come to the second party house. "Amigos! Cinco De Mayo a Cinco De Mayo St. Patrick's Day Fiesta!" The horse eats his nacho. "Bros, welcome to my Purple Prom! Rental tux is in the back." Tux Party Horse said. "Opa! Tie-Dye Toga Party!" Toga Party Horse said. "Sandy Bathing Suit Party!" Bathing Suit Party Horse said. "Makeover Madness Party!" "Family Portrait Fest!" She takes a picture. "Aerobics!" "Lobster Party here!" They go to so many parties, then Party Horse 42699, (Y/n),

Mordecai and Rigby come out of a party horse. Mordecai is wearing a pirate hat, two necklaces a toga and a floatie, and Rigby is wearing a pirate hat, a plaid shirt and white pants, and (Y/n) is wearing a necklace and a toga. "Ha ha ha ha ha! That was awesome!" Party Horse 42699. "Yeah." Rigby said, and (Y/n) yawns. "Did you get the party out of you yet, Party Horse?" She asked in between her yawn. "Aww, I still wanna party!" He said. "What? How is that even possible?" (Y/n) asked. "Have we done all of the houses yet?" Party Horse 42699 asked. Mordecai looks at the map. "Uh, yeah, I think that's all of them." He said.  "Uh, what about that one?" Rigby points at Chrissy's house with Principal Party Horse and Reverse Psychology Horse at the doorstep. "Chrissy's house!" Party Horse 42699 said.

"Come one, come all to my epic Back-to-School Party except students. Everyone except students is invited. You sure this is gonna work, Reverse Psychology Horse?" Reverse Psychology Horse shakes his head. "But..." He narrows his eyes. "Ohh!" He said. "Yep, going to that party seems like a bad idea. But maybe, forbidden partying at the home of my worst enemy and ex-girlfriend is the only way to get my partying out once and for all." He sniffs. "Chug some waters, bros, 'cause we got one more hiz-house to hiiit!" They went to Chrissy's house and find school Party Horses inside this house. "Augh! A school theme? I party to forget about school. I don't know, you guys. So far, I don't feel any diff..." Party Horse 42699 bumps into Principal Party Horse. "Oh, no." he said. "Well, well, if it isn't..." (Y/n), Mordecai and Rigby look at each other worriedly. "Party Horse!" He shakes hooves with Party Horse 42699. "What?" He asked in surprise.

"I did some thinking after our last chat, and I realized I was wrong. All this time I've been trying to teach you about knowledge and responsibility when I should've been letting you party. I guess what I'm trying to say is party on, Party Horse, party on." Principal Party Horse said. "Wow! Thanks, Principal Party Horse." Party Horse 42699 said. "And one word of advice before I let you go." Principal Party Horse points to a party palace booth. "Whatever you do, do not use the Party Palace Booth I had set up for this party." He said. "Why not?" Party Horse 42699 asked.

"It's too much partying for you, Party Horse, it's the best party in the universe in a box. Just thought I'd warn you. Well, goodbye." He leaves. "Dudes, I am so confused." Party Horse 42699 said. "Go for it, man. Maybe, this is the last bit of partying you need to get the party out of your system for good." Rigby said. "What? No! Are you crazy? This could be some kind of trap!" (Y/n) said. "Trap?" Rigby asked. "Yeah! He's obviously trying to trick him!" (Y/n) shouted. "She could be right. Party Horse, wai-" Mordecai called after him, but he was too late.

He goes into the Party Palace Booth. "Aw, yeah! Get ready for the new me, Chrissy!" He presses a button and the alarm goes off. "Huh? What is that?" He asked. "Party Horse detected. Initiating lockdown." The door is locked and Principal Party Horse appears, laughing evilly. "The reverse psychology worked perfectly! I've finally trapped Party Horse!" He shouted. "(Y/n) was right..." Rigby said. "So, wait, hold on, I'm sorry, is there, like, not a really cool party in this box?" Party Horse 42699 asked. "You fool, this isn't a party in a box, it's a box that sucks the party out of your bones permanently." Party Horse 42699 gasps in shock. "Prepare yourself, Party Horse 42699, your party is about to get pooped." He touches the lever, (Y/n), Mordecai and Rigby gasps and Chrissy appeared, running to Party Horse 42699.

"STOP!!!! Dad, stop it!" She shouted. "No, Chrissy, if this is what will stop me from partying, then I'll do it for you." Party Horse 42699 said. "But..." she said. "He said he'll do it!" He turns on the booth, and red lighting zaps on Party Horse 42699, losing his party essence as he screams and Chrissy covers her eyes, and so does (Y/n). "Oh, I can't watch!" She looks back. "Party Horse 42699?" The booth sucks Party Horse's party out of his bones, his party essence pours in a cup, the door opens, and Party Horse 42699 comes out of the booth, and is now a Non-Party Horse. "I... like eating sandwiches and... fantasy football." He said. "Eugh!" The trio cringed. " Uh, what?" Chrissy asked. Principal Party Horse takes the cup full of party essence. "At last, I've done it! I've broken Party Horse!" He shouted.

"Well done, Principal Party Horse, sir. Isn't this what you wanted, Chrissy?" Party Horse 42699 asked. "No! I've been trying to tell you all along, but you never even chilled out long enough to listen to me! I just wanted you to take it down a notch." She said. "That's all? Well, I can do that." He replied. Chrissy takes the essence cup from her father. "Change him back, Daddy!" She gives the essence to Party Horse 42699. "Drink it up, babe. Come on!" Party Horse 42699 smiles, drinks the essence and he starts to change. "Here you go, babe. I'm taking it down a notch for you." He spills out the rest of the essence. "Aww, babe!" She said wide eyed. Party Horse 42699 drops the essence cup, which breaks, and is fully back into his non-stop partying self. "Party Horse is back in business!" He shouted. Chrissy giggles. "He sure is." She said.

"WOOOOAAAAHHHHHHHH!!!!!!" (Y/n), Mordecai and Rigby said. Principal Party Horse groans. "It is about ze long game, hmm?" Reverse Psychology Horse asked. "Thanks for all your help with this, guys. You have a life-long invitation to party with me and my girlfriend." Party Horse 42699 said to the trio, and he and Chrissy giggle. "I'm good." Mordecai said. "That's alright." Rigby said. "We're good." (Y/n) said. Back at the park, Benson finishes digging up the hole and sighs. "There's nothing..." The spacecraft lands again, creating another big hole as he screams and growls; (Y/n), Mordecai and Rigby look around the hole and look up at Benson, who is also looking at the hole angrily. The trio are shocked, and the spacecraft leaves the hole, flying back up into space.