It PAYS to work for MMA star Rampage Jackson -- just ask his manager, Tiki Ghosn, who just got a $100k Range Rover on the house!!
Rampage filmed the late bday surprise earlier today ... when Tiki pulled up on Rampage's fleet of whips -- including the Range Rover Sport Autobiography Dynamic, which retails for over 6 figures after taxes and fees.
Tiki was already shocked to see more new cars in Rampage's collection ... but once he realized the Range was his, dude lost his mind.
"It's what? Shut the f**k up. Are you f**king serious? This is my car. Oh, f**k, are you kidding me?!"
Rampage said it was a gift for negotiating "the best fight contract I ever had" -- a deal he inked with Bellator back in November.