1. A golf club, used for
short shots and out of hazards (e.g., bunkers) in the
sport of golf, which has acquired an oxidized patina or surface either artificially or in the course of its use.
2. A cunning reference to seemingly innocuous yet ultimately crude phrases, e.g.., rusty
trombone, most often in conjunction with an apparent double entendre, often in mocking, tongue-in-cheek protest to the brackishness of the former.