My dad tells me that
once he and his older brother were in an art gallery for some reason, pretending to know what they were doing, and most likely fairly bladdered.

Me dad: "Daff, do you like art?"
Me nunc: "No, not really."
"Do you know anything about art?"
"Nope."
"Hmmmm. But [wink wink] you know what you like, right?"
(Deadpan): "Yeah. But it's not art."

Not a comeback per se, but unbeatable in terms of sheer comedic timing no?

Similarly, my best mate and I did A-Level psychology, and it was a fucking doss, we just sat around and argued the toss four hours a week. Just after Columbine, we were talking about Americans shooting the shit out of each other. Sensibly enough, he's saying that it's not a surprise in a country that is obsessed with guns and making guns and owning and shooting guns. A normally timid, quiet girl pipes up;

"But it's not guns that kill, it's people."

"Yeah," says Chris, immediately and crushingly, "people with guns."

All in the timing, see?
(unholysmoke, Fri 30 Apr 2004, 2:43, Reply)