We caught up with the TikTok sensation -- who blew up over his Costco-related content -- before he goes up against Marshall in the ring ... and he said NO ONE gets away with making a diss track about him and goes unpunished.

Of course, A.J.'s referring to Q.T. making a diss track titled "We Bring the Doom" -- a parody of his family's smash hit, "We Bring the Boom," that went viral earlier this year -- and he tells us Marshall's in for a rude awakening.

"He's gonna pay for all that," he said. "The doom is not powerful enough to take on the boom, and he's gonna find that out Saturday night."

A.J. won't be going it alone ... as he'll have his son, Big Justice, by his side for his return to the ring -- saying it's "The coolest thing in the world" to have his kid involved.

"I had pretty much stepped out of the ring by the time Big Justice was born," he said. "I did do one more match when he was about eight or nine years old so he could see me wrestle one time."

"Now to have him come out the curtain and come down the ramp and be ringside, I mean, who would have ever thought!"

However, what is on everyone's mind is how A.J. will look in the ring. He says everyone will be "surprised."

"To all the wrestling fans out there and to everyone that we know and love in the Costco verse, I'm going to make you proud Saturday night; I'm going to bring the boom."

Win or lose on Saturday ... A.J. made one thing clear -- he doesn't plan on this being a one-off.

"I think you'll be seeing Big Boom A.J. again."