After a visit to the doctor, a man returns home and tells his wife he has approximately six hours left to live. Of course, they go straight to bed and have some amazing, athletic sex. Half an hour later, the man asks his wife if they can have sex again. They do, and it's even more vigourous and ferocious sex. An hour later, the man asks his wife for sex again, and they have a ball-busting, rib-breaking round of sex. An hour later, the man wants it again.
"No way," says the wife. "I have to get up in the morning. You don't."