Ah the good ole pee in the water bottle method. Funny or not so funny story depending on who you are, but I was headed out to Scottsdale a couple years ago and my buddy would not pull over, so I took the water bottle and went to town.
Aaahh, that feeling of relief! Well, unbeknown to me I REALLY had to go, and the bottle was filling up. "Dude you gotta pull over I'm not even close to being done and the bottle is almost full!!" "HAHA, ya ok, don't know what to tell you". "Dude WTF just pull over!"
He wouldn't pull over, so I did what any man would have done and I pinched as hard as I could and rolled the window down to "flush" the toilet lol. His just cleaned his car and now had pee all over it and I'm pretty sure the car behind us got a good spray as well. Woops! He was pissed, I on the other hand was stoked, because I was finally done after filling up the bottle half way the 2nd time and not getting a drop on me!! 