Jon Jones Fires Back at Cormier, 'Yeah, My Wife Does Have a Flat Ass!'

Jon Jones says Daniel Cormier's attack on his wife's "flat" booty doesn't faze him at all -- telling TMZ Sports ... Cormier is right!

The UFC rivals have been going back and forth on social media -- but things got crazy personal on Dec. 23 when they brought their wives into the feud.

Jones started it ... saying to Cormier, "I could slap your wife on the ass and you could literally do nothing about it. You're my bitch D.C. that will never change."

Cormier responded ... "You couldn't do sh*t you steroid abusing junkie! I swear I would never touch your wife's flat ass lol."

So, when we saw Jones after the UFC 232 press conference on Thursday, we asked if Cormier crossed the line by going after his wife's cakes.

"He said my wife got a flat ass? She DOES have a flat ass ... but I love it!

He continued, "Oh, I love it. It's nice. It's good. I love my wife's flat ass!"