Charlie Zelenoff is an internet legend. An unstable, unemployed Californian, he has spent the last few years living the online persona of an undefeated boxer. He's made fake belts for himself, refers to fights against heavyweight champions that never actually happened, and most hilariously, "edited" it to make it look like he appeared on HBO.
(For the record, Zelenoff does actually have one professional fight. He lost in the first round to a man who was 0-13.)
Somehow, the delusional Zelenoff wrangled his way into a sparring session with Floyd Mayweather Sr. Mayweather put him through the ropes. And when Zelenoff tries a cheap shot from behind, he's put in his place by a real boxer. (Z-Money, of course, declares this sparring session with an old man that he lost an actual sanctioned bout that he won, and his professional record moves to 20-0.)