Guys what'll u do if your gf asks for water when .....?

Get her the bottle of water and be done with it. If you are a boob and this question seems to answer that, slow the car down to aprox 20 mph, tell her to jump out and hand her your pee bottle that you use on long trips and tell her that when she stops rolling that there is a creek at the bottom of the hill and tell her that when you come by this way next week, you will pick her up.