Last night's episode had Susan's new boyfriend asking her how many men she'd been to bed with. Susan told him. Naturally, he didn't like the answer.
A correct response to the "how many" question simply does not exist. Depending on the inquisitor, zero may indicate the respondent is a prude, and any number above zero could mean she's a slut.
My response would be, "Why do you ask?" Then I'd change the subject. If the dude had the bad taste to bring it up again, I'd think twice about dating him.
It's one question that reveals more about the person who asked than the one who answered.