You know how sometimes little white lies snowball out of control? It’s usually when you say something dumb, like, “Oh, yeah, I watch “Gossip Girl.”” Then the girl who sits next to you at work gives a play-by-play of each outfit the characters’ wore every Tuesday morning and you just smile politely.

But one man wrote into “Dear Prudence,” the advice columnist for Slate, to confess he’s been lying to his girlfriend about something for four years: that he has an engineering degree.

Revealing the number of people you’ve fooled around with is a lot like calling your grandmother. It’s one of those things you feel like you should do, but you really don’t want to. Why? Because you know you’re going to have a loooooong, drawn out conversation that essentially makes you feel uncomfortable. Sorry, Grams, but it’s true.

While you might lie to your grandmother about that time you jumped on top of the bar and took your shirt off, lying to your new boyfriend about your “free and easy” stage is a stickier subject. So what DO you tell him? And when?