Titter, Titter (teeheehee)

There are three pregnant women, a blonde, a brunette and a redhead, all sitting in the doctor’s waiting room. To break the silence the brunette says "Apparently the position you do when you have sex determines the sex of the baby, I was on top so I'm having a boy". The redhead then adds "Well I was underneath so that means I'm having a girl". The blonde then says worryingly "Oh shit, I'm having puppies".