With Reporting by Josh Horowitz

Fair warning, readers: If you don't want to have one of the most well-guarded secrets in Hollywood ruined for you, read no further.

Speaking with MTV News at the "Transformers: Age of Extinction" junket, Mark Wahlberg dropped a massive bombshell that fans of the robot-smashing franchise never could have seen coming.

You ready for it? Watch below and see for yourself…

That's right: Optimus Prime is real.

"He's there. He's real," swears Wahlberg. "He was there."

Bet you didn't see that one coming, did you? That's because millions and millions of dollars are spent on every single "Transformers" film convincing audiences that Prime and his fellow Autobots aren't real. But they totally are, and Wahlberg is sick of covering up for Hollywood's most private celebrities.

"See, that's what they do," the actor revealed about the various robots in the "Transformers" films. "They want to convince people that they're not real. They are real."

Eventually, Wahlberg dialed back on revealing Prime's big secret, after one of the Autobot leader's bodyguards threatened the human actor's personal safety in an off-camera segment. When the cameras started rolling again, Wahlberg revealed what it takes to act opposite an "imaginary" robot like Optimus Prime, who is absolutely, totally not real.

Really.

"You just have to go for it," he advised. "Ten or fifteen years ago, I couldn't have done it. I was too self-conscious and too worried about looking cool. But we just go out there, and I realize now that I'm not cool, so who gives a sh--, right? Just go for it. And it's actually liberating."

You know what else is liberating? Realizing that Optimus Prime is actually alive. See the completely authentic, not-at-all computer-generated Autobot badass for yourself when "Age of Extinction" hits theaters this weekend.