Well, technically speaking, is sucking a man's penis really blowing, either? It's just another colloquialism that can apply to either sex, as a "blow job" doesn't make sense either way, actually........... When a friend of mine was a total neophyte and went down on her first man, he told her to start the blow job slowly, so she took him literally and began gently blowing on his penis... Imagine how embarrassed she was when he explained that it wasn't the way to perform oral.