How about impersonating a teacher?
 

A friend if mine made a msn profile using the photo and name of a particularly unpopular university lecturer, then contacted his classmates striking up conversations.

The joke was how they felt they needed to be polite even as he was getting so outrageous it was getting obvious he had to be a fake. And yeah, we were a room full of people enjoying the show :)

But unfortunately nobody handed over any nudes.