My dog is afraid of just about everything. My wife has been using a large exercise ball (bouncing on it is supposed to help get the baby in position for delivery). Our dog can't even be in the same room with it when she is using it.
Did I mention that he is a 75 lb golden retriever?
Re: I may have the biggest wuss of a dog.
We got him as a puppy. He has no reason to be afraid of it. He's afraid of anything that seems to move by itself. And anything above his head. If you carry a box from one room to another he'll run away.
He's not afraid of people or other dogs, just inanimate objects.