Negative suggestion is pretty common. “Try not to fall off”, “Don’t push that button” are both examples. The problem is it seems to have pretty standard effects too. You fall off. You end up pushing that button. The suggestion to a person not to do something results in increasing the likelihood that the person will actually do it.
Made me wonder how often my colleagues and I use it at school. And who we might be unwittingly pushing off the tightrope.