Great topic! Gotta love those audiences, sometimes.
I did a performance of The Importance of Being Ernest in high school wherin I was playing Cecily. Her last line in Act II is, "No, men are so cowardly, aren't they?" (or somthing along those lines, it's been quite some time!).
A woman (adult, not a fellow student) in the back row jumped up, stood on her seat and shouted, "Yeah!!!! You go, girl!" I have never been so grateful to get off stage so I could laugh myself stupid in my life.
And the Christmas show I do, every year is Santaland Diaries, which, if you don't know it, is more than a little...inappropriate. Audience members tend to get quite drunk and wild, and a good time is had by all, until the hangover hits next morning. It wasn't a call back, but an audience member, male, groped the butt of our lead as he was giving his monologue from the House Left aisle.