UFC fighter Jeremy Stephens just hit Conor McGregor with the trash-talkin' KO of the century -- saying he's ready to turn up the heat with the Irishman's "hot" mom!!
You remember how the beef began -- after Jeremy called out Conor at a news conference for UFC 205, Conor whipped around and famously said, "Who da fook is dat guy?!"
About a year later, Stephens shared a photo of him and mama McGregor at a casino, captioning it "your mom knows who da fook."
And now, Jeremy's taking it all the way.