There is an interesting protocol at work at Chuck E. Cheese. This restaurant/arcade makes its money by hosting kids parties, birthday parties and such. There are a lot of kids and big parties in and out of there, and of course a lot of chaos. I would assume this makes them extra careful about protecting their customers especially kids. So here is one thing they do: when you enter there is a checkpoint at the front door. You are greeted and everyone in your party gets a stamp thats only visible under a certain kind of light on your hand. The stamp is supposed to be unique to your party.