Little Johnny's preschool class went on a field trip to the fire station. The fireman giving the presentation held up a smoke detector and asked: "Does anyone know what this is?"
Little Johnny's hand shot up and he said: "That's how Mommy knows supper is ready!"
My wife was angry. She said: "It's unfair! A guy can screw a different girl every week and he's considered a stud. But if a girl screws even two guys in a year she's called a slut."
So I man-splained it to her: "Think of it this way. If a key opens lots of locks it's a master key. But if a lock is opened by lots of keys... well... it's a shitty lock."