A variation on the rusty trombone, the rusty French horn consists of a man giving a rim job to a woman, while also fisting her. This is reminiscent of a musician playing the French horn, as he places his hand in the bell of the horn to alter the pitch of the sound.

When you eat dirt for the first time and leave your family to build a shack in the woods

To eat a girl's ass while fingering her as if you were cupping a french horn while playing it.

To suck a guys dick and fist his asshole at the same time.

It's a take-off of the rusty trombone, where you 'toss the salad', but instead of the handjob, you insert your fingers like you're playing a french horn.

Performing analingus on a female while reaching around to fist her, similar to playing a french horn.

the woman is lying on top of the man with buttox and vagina exposed and elevated. the man places left hand around womans leg, reaching clitoris with fingers, and stimulating thereafter. with right hand, he inserts however many fingers are necessary to reach maximum pleasure, while simultaneously rimming her anus. (ex. female version of the rusty trombone)