The moment to do the right thing, with Optimus and Megatron:

Optimus: When I saved that cat... originally I was just gonna ignore it, but then I got one of those special moments, you know? Those moments to do the right thing!

Megatron: I love those moments. I like to wave at them as they pass by.

Optimus: -_-

Megatron: :)

~~

The moment Cliffjumper joined the Autobots:

Optimus: *at a nice interview with Cliff* Okie... so it says here on your resume that you have a specific skill in cooking spaghetti.

Cliffjumper: You could say I'm SPAGHETTI-tacular. (See wut I did there)

Optimus: -.- *awkwardly silent*....... and you've taken classes on how to draw horses.

Cliffjumper: I get a nice RIDE out of it. :D

Optimus: -_- *blinks*

Cliffjumper: Do you get it?

Optimus: Yes I get it.

Cliffjumper: ....I do a great impression of a sausage. *lays on the ground*

Optimus:.... do you consider yourself humorous?

Cliffjumper: I DID, but boy, have you proved me wrong.

Arcee: :T Primes don't laugh, Cliff.

Guess what movie I got that from XD

~~

The moment Megatron understood an insult:

Megatron: *loses his set of marbles for a board game* Frag! *is looking for them*

Optimus: What did you lose?

Megatron: *looks at him seriously* I've lost my marbles.

Optimus: ... Everyone assumed so.

Megatron: ..hm. then I hope someone finds them soon. *walks away*

20 Min. Later:

Megatron: *thinks for a second*
....
....
...
....

Megatron: *gasp* HEY!

Optimus: It took you THAT long?