The equivalent of the rusty trombone when performed on a female. Consists of orally stimulating the asshole while manually stimulating the pussy, mimicking the actions of playing the melodies.
Jeff: What’s the best way to eat a woman out?
Greg: Give her the ol’ rusty melodica, man, bitches love that shit.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi