TV Director: That's wrong. Surely, that's wrong. (into headset) No, not you. (on PA) GET. HIM. OUT!
Pretty much anything John says or does throughout the movie.
Special mention must go to his truly epic scene in the bathtub. He cheerfully ignores the conversation going on ten feet away from him, preferring instead to play a highly noisy and splash-y game with toy torpedoes.
"Rule Britannia! Britannia rules the..." SPLASH
"If I Fell". They sing it to Ringo.
The entire scene's worth of "Can't Buy Me Love." Of particular note: shots of John, Paul and George, each jumping spectacularly into the air...followed by Ringo readying himself for a similarly gigantic leap and doing this pathetic little hop with his arms at his sides.
The total lack of reaction on the part of all four Beatles to the revelation that there's a man locked in the closet. Even better, Ringo and George separately walk up to the closet, look inside, close the door and casually walk away, although they appear to be mildly concerned.
George:[After checking the closet on Ringo's claims of a man being inside] He's right, you know. John: Well, there you are.
The fact that the novelization of the movie has gone on record as being the first book in the English language to contain the word "grotty."
Indeed, the movie itself is where the word came from.
This line, coming from Ringo:
"There you go, hiding behind a smoke screen of bourgeois clichés."
Ringo's reaction after he accidentally causes a well-dressed woman to step right into a sinkhole.
"Ringo, what are you up to?" "Page five."
The sight of all the young girls swooning and going nuts over the Beatles during their end concert.
Simon Marshall's assistant tries to whisper to him "That's George Harrison". Not listening, Simon sternly responds "Don't breathe on me, Adrian."