Not quite a "know you're a geek when..." but still amusing:
A programmer is walking down the street when a frog cries out, “Help! I’m a princess! If you kiss me, it will end the curse!”
The programmer glances at the frog, picks it up, and puts it in his pocket.
“What? No!” the frog cries. “Please, if you break the curse, I’ll stay with you for a week!”
The programmer pats his pocket but otherwise does nothing.
“My god,” the frog pleaded, “I’ll do anything you want if you bre—”
“Listen,” the programmer interrupted. “I’m a programmer and I don’t have time for a girlfriend. But a talking frog? THAT’S cool.”
(P.S. I did not write this, I take no credit for anything other than passing it along.)