Wow there were SO many really great lines, but ones that are memorable to me:
"He's adopted" probably my favorite because A. it was so unexpected and B. it was so well delivered.
"Hulk..........smash!"
Tony calling Loki .....damn I cant remember exactly, but something funny referring to his horns. What was it? ** ah, "Reindeer Games" just found it above.
Tony calling Thor "Point Break"
Tony saying "Well how about that" when Jarvis said "power at 400%".
Hulk "Puny God" even though I'm pretty sure no one heard it because they were still laughing hysterically.
Tony "Please tell me no one just kissed me".
Fury "Well tell me if Ultimate Power needs a magazine or something".
Coulson "So that's what it does".
Widow "This moron is giving me everything".
Coulson "I watched you while you were sleeping".
Fury "Yes I got the order. But because it's a stupid ass order I am choosing to ignore it".
Banner "I was in a dark place. I put a bullet in my mouth and the other guy spit it out".
Tony had so many funny quick witted comments, I seriously wonder how many were scripted and how many he came up with on the fly.