I was just thinking of an old movie with the deceased British actor Terry-Thomas (and yes, the hyphen is apparently part of his stage name). In the movie, there is an exchange that goes something like the following. He is at a party and a woman comes up and says "Why is it you? We haven't run into each other in, what?, 10 years or more." His retort is "Rather a nice interval, don't you think?"
In another movie (or perhaps the same one: I'm not sure) another woman (or perhaps the same one) announces she'd like to show him her grandchildren. His retort: "I don't want to see your beastly pictures!"
Anyway, I've always loved a great retort. In America, we have Dorothy Parker, who was almost undoubtedly the most acidic wit we've ever produced.
At the time of this quote, she was attempting to go through a doorway at the same time as Clare Booth Luce, with whom little love was lost. The story goes that Luce stepped out of the way saying, "Age before beauty." Parker didn't skip a beat, replying "Pearls before swine" (a Biblical reference)
Do you folks have any precious examples of witty exchanges like that?
Here is an exhaustive list of Dorothy Parkerisms. Not all are retorts. Some are just daffynitions such as, "If all the girls attending (a Harvard prom) were laid end to end, I should not be surprised."
Here's a bunch of them.. http://www.drmardy.com/repartee/historygreatreplies.shtml