Jimmy Fallon had Bill Gates on NBC's "The Tonight Show Starring Jimmy Fallon" on Wednesday night to talk about his foundation's new invention that turns sewage into drinking water.

That is something we talked about a couple of weeks ago on "The Free Beer & Hot Wings Morning Show."

For his visit with Fallon, Gates brought two glasses of water with him. One was filled with bottled water and the other was filled with purified sewage water, also known as poop water.

Fallon didn't know which was which, and was challenged by Gates to drink a glass and guess which one it was. Gates then drank the other glass.

Check out the video to see if Fallon chose correctly!

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