A mathematician gives a talk intended for a general audience. The talk is announced in the local newspaper, but he expects few people to show up because nobody who is not a mathematician will be able to make any sense of the title: Convex sets and inequalities.
To his surprise, the auditorium is crammed when his talk begins. After he has finished, someone in the audience raises his hand.
“But you said nothing about the actual topic of your talk!”
“What topic to you mean?”
“Well, the one that was announced in the paper: Convicts, sex, and inequality.”