A young couple has sex, and when they're finished, she looks in the box of condoms, and there's only six left out of twelve.
She says, "What happened to the other five condoms?"
He says, "I, uh, masturbated with them."
That night she tells a male friend what happened, and she says, "Have you ever done that?"
He says, "Of course. All the time."
She says, "Really? You've jerked off into a condom?"
He says, "Oh, no. I thought you were asking me if I've ever lied to my girlfriend."