Human urine. It's what we don't need and is what's leftover. I know there are some people who are into the "waterworks" but let's not get on about that just yet.
All afternoon, Kathy was drinking a 2 liter of diet soda with a straw and eating smoked salmon much to the displeasure of her coworkers. The only time they felt better was when she when to provide the toilet with her leftover water.