A "sexual aid" used at the base of the penis, usually made of leather, which serves the dual function of both constricting blood flow for hardness as with the use of a "cock ring" and also as a "penis bib" of sorts, protecting the cock and balls from unwanted fluids as when engaging in anal sex or copulation with a menstruating female.
Ahh Dude! I got to the party so late, like 6 other guy's had already boffed Jenny, so I had to use my "leather donut". I think the chick may have been on the rag anyway.
by Conrad Duquesne May 29, 2008