Even though I come away believing half the stuff is made up, Overheard in New York and Overheard in the Office are consistently entertaining. Recent entries:

Girl: Isn’t your dad Swiss?
Guy: No, he’s Swedish.
Girl: Oh, that’s right: people are Swedish, things are Swiss. Well, actually, they’re interchangeable.
Overheard in New York

Engineer #1: What the hell were you thinking when you wrote this code?
Engineer #2: Boobs.
Engineer #1: Huh?!
Engineer #2: Truthfully, it’s likely I was thinking about boobs.
Overheard in the Office