THANK YOU @LionessSister for the spam!

Lance is Liam Neeson (sp?). He keeps screaming "I WILL FIND YOU. AND I WILL KILL YOU." To everyone he sees. People have started avoiding him.

Keith dresses as a cowboy. He has the accent down perfectly. Some members of the team are starting to suspect he's Texan. (cough cough)

Hunk dresses as Gordon Ramsay, screaming at people to "COOK THAT MEAT" and slapping bread on the sides of people's heads, demanding to know what they are until they say "an idiot sandwich."

Allura needed some explanation as to what "this Earth custom called Halloween" is, but she got into the spirit quite quickly. (She may even have to compete with Lance for level of enthusiasm.) She let Pidge and Hunk help her dress up as Sailor Moon, having seen the show before.

Coran went to Halloween in some weird fluffy outfit, claiming it was a "Wenderian Schpiffletrot." None of the humans want to know.

Pidge literally went as a mannequin head girl from Vine. Apparently that meme never died, and is now known across the universe.

Everybody gathered in the control room of the castle ship, waiting for the party to start. Allura, Coran, Keith, Pidge, Lance and Hunk were there, but where was Shiro? There was a yell and a loud THUNK as Shiro hit the wall in front of the door. He walked in and all laughs and conversation fell silent.
He
Was
The
Halloween
King.
Shiro had somehow made a Voltron costume, complete with the headgear and everything. The painted cardboard looked so close to metal that even Allura was surprised. Shiro smiled mischievously through his silver face paint and pulled Voltron's flipping sword from a holster on his back.

"Trick or treat everyone."

The group decided to never question his art skills after that.