Damn! I had to read 53 WRONG definitions of the RUSTY TROMBONE! It has nothing to do with gay dudes, reach arounds, or assholes. It's when you fuck a chick ON HER PERIOD, then she immediatly blows you. Blood has a distinct taste that can well be described as...rusty.
Guy#1: Yeah, so did you hear Blake was dating that weird, goth, "Twilight" chick?
Guy#2: Hey, I bet he gets the old rusty trombone no sweat.
The act of performing anal cunnilingus while reaching up above the testicles to manually administer quick up and down motions to the penile shaft; resulting in a violent yet pleasant explosion. It is then customary for the female to then give a quick blow into the anus for good luck, the lips blowing into the anus sounds very similar to a trombones sweet melody. This was introduced to the Americas in the late 50's.
While receiving a rusty trombone I lost control of my bowels.