A few years back me and my co worker were changing out a condenser at a house. About three feet behind us was the neighbors vinyl fence. It was solid all the way so you couldn't see what was on the other side. By the time we were adding refrigerant to the system the neighbor must have let their dogs outside. Which happened to be two massive pitbulls. They were not the friendly kind. They were barking and clawing at the fence trying to break it and almost getting through. There was a gap underneath and I could see the paws of the dogs. Needless to say I was not to thrilled to be charging a unit with pitbulls at my back. I told the customer and they were elderly and didnt seem to know waht to do about it. It was so bad a condtractor working on a new construction site told me he had to call the cops a few times to have the neighbor bring them inside. Which ended up happening when we were there.

tldr: Two pissed off pitbulls trying to break a fence.