Midway through his interview, Fallon, 40, told Brand he wanted to change direction slightly and introduced his recurring game, Word Sneak, which challenges guests, and Fallon himself, to input a bizarre word into conversation without your opponent noticing.
Instantly engaged, Brand went off on one of his trademark tirades — but rather than pushing for world peace or the end of capitalism, Katy Perry's ex-husband was just trying to create a reason to say the word "loofah."
A flabbergasted Fallon pushed his way into the conversation but was instantly busted by his competitor for his use of "frisbee."
As the segment progressed, Brand, 39, got more and more wordy.
"This game makes me feel like I'm trapped in a prism of words, I'm in a vortex of words, you've trapped me, you've tricked me, I feel like I'm an instrument you're playing," the loquacious celebrity spouted.
Watch the video above to see the whole, mind-boggling episode!