A comedian use to have a catch phrase, "Here's your sign", when people would do stupid things that you would think you would not have to warn them about. I had my first display show with a 6' Eastern Diamondback Rattlesnake. I can't count how many time my snake team or I had to tell people to not tap on the glass and tease the Rattlesnake. For the next show I made a sign and put it on the front of his tank that read, "Don't tease the Rattlesnake". I mean seriously, what would happen if the glass broke and the snake was able to get out. I guess it would be the last time they would do that. But believe it or not I still had yell at 3 people to not tease the snake.
I guess at the next show I'm going to have to make signs that people can wear around their neck, that says, "I'm stupid", and every time I see someone banging on the glass, I'll say, "here's you sign".