Dax Shepard says he was once threatened by Mike Tyson at an NBA All-Star Game

Dax Shepard almost got knocked out by a former heavyweight boxer!

The CHIPS star was recently a guest on Watch What Happens Live With Andy Cohen, where he was asked to reveal the meanest thing a celebrity has ever said to him.

WATCH: Kristen Bell Interviews Dax Shepard Who Gushes Over Her: 'You Are on a Cellular Level Likeable'

Shepard, 42, explained that it all went down at an NBA All-Star Game. He was joking around with Tyson when all of a sudden, the 50-year-old athlete allegedly said, "If you don't take your hand off my shoulder, I'm gonna break your f***ing head open."

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"I had met [Tyson] the week before and he really liked me, and then I was way too familiar with him, I was grabbing his shoulder and stuff, and then he didn't remember me and then he understandably told me to get my hand off of him," Shepard continued. "And then I thought he was joking and then he escalated it and then I took my hand off his shoulder."

Perhaps that's karma for blackmailing his wife, Kristen Bell?

More on that -- and their ongoing feud over home décor -- below!

WATCH: Kristen Bell and Dax Shepard Adorably Spar Over Home Décor on Instagram