An unlikely excuse used to explain away a suspicious wound or injury. For example, when the police question a murder suspect, they find that he has some cuts or scratches on his face, consistent with the type of wounds that the perpetrator would incur in that sort of crime (perhaps because someone with a knife fought back). When asked where he got them, nine times out of ten he will say he Cut Himself Shaving. Likewise, a guy who beat someone up will often say that the victim "fell down some stairs" or "ran into a door" whenever being questioned by the cops.