If I stick my bare hand in my tank, which I don't do often, my clown will come out of nowhere, grab the fleshy part between the fingers, and shake back-and-forth like a little freakin' shark!! Doesn't really hurt, but you sure can feel it. The first time he did it, it scared the CRAP out of me, and I almost knocked my tank over from jerking my hand back so fast....
If I have rubber gloves on, he pays my hands no mind whatsoever.
Wanna calculate the cost of that new reef tank?? Take your worst nightmare, double it, and you're halfway there.