A son takes his elderly father to the doctor.
The doctor says, “I’m sorry, sir, but the outlook is grim. You have a rare form of cancer and you’ll be dead in a year.”
As they’re driving home, the father says, “You know, I’m not depressed. I’ve lived 75 great years. Tonight let’s go out and celebrate my good, long life!”
That night they’re at the bar and the father is surrounded by all of his friends and he says, “Yup, I’ve got AIDS. I’ll be dead in a year.”
At the end of the night, the son is driving his father home. He says, “Pop, you’ve got cancer. Why did you tell all your buddies you have AIDS?”
“Because after I’m dead, I don’t want them fucking your mother.”