Took the dog to the vet

Bert 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 "Bert, why should I do such a terrible thing?"

"Because my mother-in-law's arriving tomorrow,

Spoiler:

and I don't want anything to make her think she's welcome".