The Silent Rule

A young man buys a motorcycle and the clerk says
**When it rains, you should rub vaseline on the wheels to keep them from rusting.**
So the young man always carries vaseline with him.
Later, his girlfriend's family invites him over for dinner. She says
**We have a silent rule for dinner. Whoever speaks first does the dishes.**
He says okay and goes to dinner.
During dinner no one really makes a noise. He thinks
"If I kiss my girlfriend now, no one would say anything."
So he kisses her and no one says anything.
Then he thinks
"If I grope her tits and ass, no one would say anything."
So he does and no one says anything. He gets all fired up fucks her right there and no one does anything. Then he looks at her sister and thinks
"If I fuck her, no one would say anything."
So he fucks his girlfriend's sister and no one says anything. Then he looks at her mother and decides to try that too. So he fucks her too and again no one says a thing.
Right this moment he sees that it's raining. He takes the vaseline out from his pocket and at that moment his girlfriend's father says
"No, stop. Fine, I'll do the dishes."