Whether you are a new flyer or an old flyer, common sense should tell anyone that you don't stick your hand in the fan when checking the oil in your running car. You don't do jumping jacks under a low ceiling fan. You don't clean grass from underneath your mower with it running. Any person from a very young age can look at something and tell if it is dangerous or not. The problem is that some people are just a little more careless than others, and it has absolutely nothing to do with how much flying time they have under their belt. So I agree that the "you will cut your hand off kid" thing should be left for just general conversation and not directed towards only new pilots. Getting bit by the prop is NOT just a new pilot thing. Props are not prejudice who they bite!