I'll have to say that I have had my stupid moments. When I got my start in aircraft modeling, control line, to stop a Cox .049 you threw a rag into the prop. No fuel line to pinch. Then I got a Fox .35 stunt. First time I tried to start it with fingers. The prop came around and bit me. It hurt enough that I used a screwdriver handle from then on. I didn't have anyone to talk to about the hobby so I learned averything the hard way. Once I had the engine running and was watching dirt going up the fuel line toward the carb. Without thinking I stuck the screwdriver in the prop. The prop survived, I got away with a few scratches, and it hurt like hell. I didn't think to either pinch the fuel line, or to pull it off the carb, but knew it was way too close to stick my finger between the cylinder and prop.