Yeah, Ive done that before....this one time my gf and i were on a road trip. she really had to go and we couldn't find a pit stop, nor could she go pee out in the bushes (she was horrified of snakes, and when she got out of the car to pee in the bushes, she saw one and immediately jumped back in. So, i offered to drink her piss and spit it out the side of the window when we got going again. She did the same for me later on that trip, and it eventually became part of our sexual relationship. go figure