A man wakes up one morning to find a gorilla on his roof

A man wakes up one morning to find a gorilla on his roof.

So he looks up the yellow pages and sure enough, there's an ad for "Gorilla Removers". He calls the number, and the gorilla remover says he"ll be there in 30 minutes.
The gorilla remover arrives and gets out of his van. He's got a ladder, a baseball bat, a shotgun and a huge, ferocious looking dog.
"What are you going to do?", the homeowner asks.
"I'm going to put up this ladder against the roof, then I'm going to go up there and knock the gorilla off the roof with the bat. When the gorilla falls off, the dog is trained to grab the gorilla's testicles and squeeze. The gorilla will be subdued enough for me to lock him in the cage in the back of the van.", says the gorilla remover and hands him the shotgun.
"What's the shotgun for?", asks the homeowner.
"If the gorilla knocks ME off the roof, shoot the dog."