Super secret bonus answer?

I've caught side show bob quite a few times, he's not even announced sometimes, he just shows up in a neighbours Springfield......also, He's done something that I've not seen before or heard of, but a couple of times when I've tapped on him, he does a hand stand......no lie, he really gets on his hands and puts his feet in the air. I keep trying to make him do it, but I'm not sure what it is I've done to make it happen. Could be a glitch, or not.