What fun ways (besides the obvious) have you incorporated watersports into your BDSM play?

I was just watching a video in which the girl was tied up standing legs spread (w/ arms bound) and had a metal pail hung from her labia. She wasn't allowed to cum until she had peed enough into the pail to make it fall off, and they teased her with whips and vibrators to make it harder for her to aim the whole time.

I thought it was hot and interesting, so I wondered if anyone here had tried something like that and had some interesting ideas to share.