You don't even need a knife, you already have several of them - spinning. http://www.dailymail.co.uk/news/article-2413231/Roman-Pirozek-Jr-Man-decapitates-remot

You don't even need a knife, you already have several of them - spinning. http://www.dailymail.co.uk/news/article-2413231/Roman-Pirozek-Jr-Man-decapitates-remote-control-helicopter.html http://www.dailymail.co.uk/news/article-2413231/Roman-Piroze... - "... was pulling a stunt with the chopper at a Brooklyn park Thursday afternoon when he lost control and the RC device flew into his head. The blades sliced off a piece of his skull and slashed his throat."