I recall hearing or reading someplace that Viking Berserkrs went into battle with erections visible. To me this sounds like you’re simply asking for trouble (warriors with their penises cut off aren’t very efficient – they tend to be distracted), but maybe it’s supposed to be a macho or intimidation thing.
In any case, I haven’t been able to find anything on it in books or on the Internet (although I have found some interesting research on attitudes toward size in the Sagas. You will, too, if you look.)
So is this an Urban Legend? Or is this acually recounted somewhere, but it’s obscure?