an imaginary musical note, which, under ideal circumstances, does not exist; a J# (jay sharp) is any musical note that should be played # (sharp) according to the key signature of the musical selection, but is (unintentionally) played as natural by the player, which will oftentimes be young and inexperienced, or careless.
Frustrated by the number of missed key signature notes, the director yells, "Don't forget your J#s!"
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!