J.J. Watt locked himself out of his awesome cabin in the middle of Wisconsin Friday ... in freezing cold weather ... and it was hilarious!!
It all went down after J.J. completed a training session in his personal gym (located in the barn on the property) ... when Watt realized he forgot to bring his keys.
Ya gotta watch the video ... we learned a lot about the Houston Texans star including the fact he's got a beer tap in his gym!!!