I read an article in a magazine some years ago documenting how people had walked through idling props without being touched, usually big radials. On one occasion, the guy realised what he had just done and fainted!!
My school metalwork teacher did his national service in the RAF maintaining Washingtons (Boeing B-29). He described this occurred on their squadron. I've also heard it mentioned in the case of a Vickers Wellington.
Mechta Senior did some trials work on HMS Eagle, and in the relatively short time he was aboard, the cruise included a burial at sea for someone who had walked into a propeller of a Fairey Gannet. Assuming both engines were running, you wouldn't stand much chance with a contra-rotating prop.