watercycle
The act of getting up to both empty your bladder and also refill the vessel that contained the drink that made you need to go in the first place. The expression is not limited to water, as many other beverages can fall under the umbrella of the watercycle, including Big Red and coffee. Unsurprisingly, the watercycle is often referred to as being "ridden".
Hey, guys, I'll be right back. I need to ride the watercycle.