Here's another thumb one to add to this thread to remind everyone to be careful;

One of our club members, very-very-experienced, was helping another club member tune an engine last summer. He was behind the prop where he should be, but while tuning the needle, his hand touched the hot engine. Well, the instinctive "jerk-your-hand-away-from-the-heat" happened, and his thumb went into the prop (APC I think, but not sure). He was "lucky" and lost only a chunk of meat from the side of his thumb (from the edge of the fingernail at about 45 degree angle down to the center of his thumbprint).

Moral of the story is' be careful even if your behind the prop.