Lately I've twice seen beginners receiving instructions adjusting their engines while reaching over the prop from the front of the plane. While I certainly value my fingers, that places the artery in your wrist right over the prop. Incredibly the guy reaching over the prop turned out to be the instructor in one case. I've also observed experienced guys starting 100cc plus engines by themselves without even tying down the plane.

I am amazed at the carefree attitude many people have when placing body parts within inches of a sharp object rotating at several thousand rpm.