UFC's Daniel Cormier -- I've Got a Date with Mariah ... After UFC 187 Fight

Ronda Rousey eats chicken wings. Boxer Danny Garcia immediately has sex. But Daniel Cormier says he has a different post-fight ritual planned for UFC 187 ... he's going to Mariah!!!

Since the UFC star is set to take on Rumble Johnson in Vegas this weekend ... Cormier says he plans on taking in a local show the night after the fight -- and he picked Mariah over Britney and Celine!

But Cormier says he's not usually a "Diva" kind of guy -- admitting he's OBSESSED with Boyz II Men ... and has basically become a regular at their shows!!!

Cormier's not joking ... he's a bona fide B2M'er ... and he's damn proud of it.

Check out the clip.