A boyfriend and girlfriend want permission to go to the prom, but the girl's father refuses.
"Absolutely not!" the father says, shaking his head angrily. "There'll be dancing there, and dancing can lead to sex and sex to pregnancy! Do you want to be pregnant at 18?"
"We won't be having sex, Dad! We just want to dance and have fun!" the girl tells him. "You probably won't even approve of us having sex even if we got married!"
"Of course, I will!" the father tells his daughter and her boyfriend. "Sex is allowed between a legally married couple."
"Can we do it in places other than the bedroom, like on the countertop in the kitchen in an airplane washroom?"
"Yes, since you'd be a legally married couple."
"Can we do it in all those weird positions, and can I be on top?" she asks.
"Yes, as long as you're a married couple," the father replies.
"Can we do it standing up?" the girl asks.
"NO!" shouts the father.
"Because It could lead to dancing!"