It was just a few years ago that 50 Cent and Floyd Mayweather were playing with their millions together. Now they're cattish enemies who've made headlines again for trading shots.

Mayweather is still an undisputed champion who's on the verge of retirement, but he's recently been more recognized for his beefs with T.I. and 50 Cent. The boxer did an interview with MLive.com and made some disparaging comments against his antagonists, whom he left unnamed.

"What's so crazy is this: You know, when people are not relevant, and they're not moving units like they were once moving ... you've got to realize, I've been relevant for 18 years," Mayweather says in the interview.

Bad move. Nelly allegedly stole Mayweather's ex-girlfriend Shantel Jackson away from him after they broke up earlier this year. Then there was the altercation with T.I. at a Las Vegas Fatburger in May.

Fif didn't focus on the Fatburger incident, but he definitely made fun of Mayweather for losing Jackson to Nelly.

"Woke up. I look at the computer ... the computer say 'Floyd said f--- T.I., f--- 50, f--- Nelly,'" 50 Cent says in an Instagram video. "I'm like what he say f--- me for? Nelly f---ed your first baby mama Melissa. Then took your f---ing fiance. [You should] say f--- that n----."

To add further insult to injury, 50 Cent follows up with a video saying that instead of the ALS Ice Bucket Challenge, he'll donate $750,000 if Mayweather can read one page of 'Harry Potter' (a popular but grade level reading book) without screwing up.

The G-Unit leader has made a few shots at Mayweather since they broke off their friendship in 2012 -- that includes one referring to the T.I. skirmish. Mayweather hasn't made a direct response since Fif attacked his reading ability earlier today.

Watch Floyd Mayweather Attack Hip-Hop Artists' Relevancy

Watch 50 Cent Bash Floyd Mayweather for Taking Shots at Him