Steve Aoki Nut Shotted By UFC's Ken Shamrock!

Here's video of UFC Hall of Famer Ken Shamrock schoolin' Steve Aoki on the finer points of being a fighter -- like taking shots STRAIGHT TO THE BALL BAG.

The painful intro-to-MMA sesh went down at the UFC Performance Center in Vegas ... where Steve was filming a music video for his new EDM collab with Laidback Luke, "It's Time" (get the reference?).

Ken, who was playing Aoki's trainer, was slappin' abs on a core workout when he missed low ... and Steve immediately tapped out on account of the "electric shock across my whole groin."

"Instant stoppage right there," Shamrock said.The full video -- ft. an Aoki vs. Luke DJ super-fight and Octagon announcer Bruce Buffer -- drops on Friday ... but we…