rock waterfall

Urinating on one's own scrotum, often by accident.

Steve's pants were too tight, and it was very hot out. He had to keep drinking water, so inevitably he wound up having to pee. He entered a McDonald's, and when he got into the bathroom, he realized he also needed to poop. So he sat down on the toilet, and as he let out his stream of urine, he did not yet realize the degree to which sweat had glued his scrotum to his shaft, and received a rock waterfall.