Pretty much anything Morph says or does, from immitating numerous movies to morphing into a cricket team poster.
One particular instance come to mind, where the team stopped off at a world where they just had to foil a bank-robbery, and earned a little R&R. Since the rest of the team wanted to go to a nude beach,- and Morph wasn't exactly the poster-boy for hormone-suppression at the time- They convinced Sunfire (Mariko Yoshida) to take him lingerie shopping while they had fun. It turns out he knew they were trying to get rid of him the whole time (just not why), and after an afternoon/evening of friendly bonding with Mariko, the two decided to get revenge on their teammates by pelting them with a Morph-catapult of water-balloons. Only...
Morph: "Water-balloons"? Weren't you paying attention? I filled these with beer.
Sunfire: Morph, you are bad.
Morph: I am so bad.
Sabretooth, after getting his ass kicked by Psylocke.
"I'm either in love or I'm gonna kill her. Prob'ly both." Turned out to be the former after all.