Kevin says he thought he could beat his friend in a race ... but the guy he was up against is former NFL running back Stevan Ridley, and now he's regretting even entertaining the thought he could actually outrun a pro athlete.
Sitting in a wheelchair on his porch, Kevin says the injury is one of the dumbest things he's ever done in his 44 years on earth ... and he says it's a sign he needs to slow down and act his age.
Kevin's hilariously questioning why he even raced Stevan in the first place ... joking he was trying to be the fastest man at the BBQ, and the comment section is filled with celebs chiming in.
The fact Kevin's laughing about it makes it seem like he's not too concerned with his torn muscles ... after all, he's had serious back issues from a near-fatal car crash and went through a grueling rehab.
Still, Kevin's giving himself the title of the "stupidest man alive."