This guy has always dreamed of owning a Harley Davidson. One day he
has finally saved up enough money so he goes down to the dealer. After
he picks out the perfect bike, the dealer tells him about an old biker
trick that will keep the chrome on his new bike free from rust. The
dealer tells him that all he has to do is to keep a jar of Vaseline
handy and put it on the chrome before it rains, and everything will be
fine. He happily pays for the bike and leaves.

A few months later, the young man meets a woman and falls in love.
She asks him to come home and meet her parents over dinner. He readily
accepts and the date is set. At the appointed time, he picks her up on
his Harley and they ride to her parents house. Before they go in, she
tells him that they have a family tradition that whoever speaks first
after dinner must do the dishes. After a delicious dinner everyone
sits in silence waiting for the first person to break the silence and
get stuck doing the dishes. After a long fifteen minutes, the young
man decides to speed things up, so he reaches over and kisses his
woman in front of her family. No one says a word. Emboldened, he
slips his hand under her blouse and fondles her breasts. Still no one
says a word. Finally, he throws her on the table and has sex with her
in front of everyone. No one says a word.

Now he is getting desperate, so he grabs her mother and throws HER on
the table. They have even wilder sex. Still no one speaks. By now he
is thinking what to do next when he hears thunder in the distance.
His first thought is to protect the chrome on his Harley, so he gets
his jacket, reaches in his pocket and pulls out his jar of Vaseline.
And the father says "Okay dammit, I'll do the dishes!"

Good one.