Art attempting to make Wrex lose The Game when they reunite on Tuchanka in the sequel. The fact that he subsequently makes every single krogan in the area lose the game makes it funnier. Cue Art being absolutely gobsmacked, followed by a very confused Sturge trying to figure out what the game is.
Absolutely everything that Legion says during MV 2's epilogue chapter
Legion: Addendum: Let's get this party started."
During Tali's trial, Art, Thane and Kasumi are a bit late. Art then bursts in, in an homage to The Dark Knight by bursting into the trial, firing his shotgun into the air one-handed and yelling, "Good evening ladies and gentlemen! We're tonight's entertainment!"
Jenny and Nogond singing "Art and Tali sitting in a tree..."
Legion learns how to use 'That's what she said' in conversation.
Kasumi and Art chat about him and Tali. Right afterwards, she asks 'Anyway, how's your sex life?'