You found the key to my joke vault?
A man takes his rottweiler to the vet.
"Can you have a look at him," he says, "I think he's cross-eyed".
So the vet picks up the dog and examines him.
"I'm going to have to put him down," says the vet.
"Why, just because he's cross eyed?"
"No," says the vet "because he's heavy!"