The act of mounting and riding a corpse's stiff penis. This can be preformed by men or women. The name comes from the penis being blue and hard like a horn.
"that chick is up for anything, I even heard she did a Blue Rhino once"
when one waits until he becomes blue-balled, then runs full-speed at his partner, who is already bent over, and busts into his ass immediately upon penetration.