I'm thinking of starting humping my dog in front of guests.
Why would you hump your dog at all?
It would be funny would it not.
Even if you are just making a joke, thrusting on your dog in front of everyone is crude and insensitive. Leave your animals alone and find other ways to joke around with your friends.
Who cares. Dogs like it.
Are you sure that your dog likes it? I would find someway else to make your friends laugh, it is not okay to even pretend to have sex with an animal.