Joseph took his Saint Bernard to the vet.
“Doctor, “he said sadly, “I’m afraid I’m going to have to ask you to cut off my dog’s tail. “
The vet stepped back, “Joseph, why should I do such a terrible thing?”
“Because my mother-in-law’s arriving tomorrow, and I don’t want anything to make her think she’s welcome. “
This joke is included in the Black Book of Jokes. You can order it from here.