Impotent? Incompetent?

Last night, SD and I were hanging around playing our instruments (me: bass clarinet; SD: trumpet), and we were discussing the other trumpet players in her class. One, in particular, is really annoying. Said person will go through and write the letter(A, G, F#, etc) under every note on her sheet music. This is, obviously, bad form for a player. I asked SD if this other person was any good musically. SD's words were "No, she's completely impotent".

Wait. WHAT?

I asked her if she meant "incompetent", to which she reponded "I don't know what that means". I then proceeded to tell her that "incompetent" means that this person is inadequate, or not fit to perform the function they're in. "Impotent" means that this trumpet player (a female, at that) is unable to get and keep an erection.

The look of abject horror was priceless. She then said that she hoped she hadn't used the incorrect word too much (like, say, with her teachers).

I hope so too.