I just read this joke in Esquire this morning. Apologies if it has already been posted.
A man goes to his doctor and discovers that he has only one day to live. When he goes home, he decides there is only one thing he wants to do, and that is to have sex. After several hours of intense sex, he turns to his wife, and asks for one last time. With exasperation, she says “Look – I have to get up in the morning – you don’t!”