Just because Bill Gates is busy saving the world doesn't mean he doesn't have time for feces-related pranks with Jimmy Fallon.

The humanitarian stopped by The Tonight Show Wednesday and discussed the Janicki Omniprocessor, a machine that turns sewage into clean drinking water, electricity and ash. Then he tricked Fallon into drink some of the poop water.

We're guessing Fallon will be sticking to Evian from now on.