Evolution has afforded every animal in the world the tools perfectly designed for its survival, whether it be claws, venom, horns or whatever it is that cockroaches have.
But every once in a while, evolution makes a mistake and leaves a totally useless trait in an entire species. That's bad news for them, but good news for us, as it can be amusing as hell.
Specifically, there are traits that allow the animal to be completely immobilized with a touch, push or rub. That means that with some practice, anyone can immobilize a shark by rubbing its nose or make a lobster stand on its head.