I would like to share some advice. On the day you're supposed to pee in a cup, don't go running that morning and get dehydrated. And don't decide on that very day to cut back on coffee and have only one little cup of espresso.
And when the chump-ass rookie pee-in-the-cup tech tells you to drink "no more than eight glasses" of water from this fountain to prime the waterworks, he actually means "drink eight glasses." Not four. It's not enough. I hope that helps. Oh, and take a magazine.