Quite similar to the Rusty Trombone with the following two changes: 1) the receivers cornhole is not to be licked but rather blown on/into with buzzy lips like a tuba player; and 2) the giver should wiggle their fingers on the receivers wang as if playing with tuba valves rather than stroking it like they're moving a trombone slide.
She was really drunk last night and I think she got bored with the rusty trombone I made her give me so she just started fiddling with it and making raspberries like a baby. It was my first Rusty Tuba from a woman!
Much like a rusty trumpet, only with a much larger partner.
Yeah, your mom had a great time when I gave her the rusty tuba.