It's become so common to see celebrities tweeting at each other that most of it happens without much fanfare. But this thread is not only worthy of making news, it's something that should definitely turn into a thing.

Justin Bieber challenged Tom Cruise to an MMA fight, and then Connor McGregor chimed in and I hope the challenge is accepted.

I think this would be a hilarious match up and worth watching, since Tom is barely over 5'2" tall and Bieber is hardly 100 lbs soaking wet!

If you could pick two celebrities to go head-to-head in the octagon, who would you choose?