Steve Aoki's Nuts Get Slapped By UFC Legend 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 superfight and Octagon announcer Bruce Buffer -- drops on Friday ... but we got a sneak peek for all you candy kids.

Fun fact: Laidback's a WORLD CHAMPION Kung-Fu fighter ... so we hope Shamrock taught Steve some other MMA skills, too.