Conor McGregor says Nate Diaz owes him a big fat thank you for the paycheck he's about to get for UFC 196 -- and says Nate can even work it off with a few dances.

Conor avoided any racial slurs during Thursday's pre-fight news conference in Las Vegas, but still blasted Diaz ... calling him a "scared little boy" who has a "bully mentality until a real man shows up."

Check out the video, 'cause things really got intense when they started talking money and Conor said, "Dance for me, Nate! And don't look me in the eye!"

And yeah ... things got physical during the pose down.