The history of the otopenile phenomenon surely begins with the early Church Fathers' explanation of the insemination by angelic means of the Virgin Mary, with the "Word of God" doing the dastardly deed by means of aural entry?
I believe it existed before Barbelith, as many years ago I knew a guy who liked to threaten: "I'm going to stick my dick in your ear and fuck some sense into you."
Needless to say, it remains one of my all-time favourite lines.
I seem to remember a particularly gross part of Marilyn Manson's autobiography which featured a member of the band shouting "I'm gonna cum in your useless ear canal" at a deaf groupie. Tasteful.