The UFC commentator/podcast titan/comedian had parked his truck at LAX during his Summer vacation to Europe ... and when he got back, he noticed the whip was covered in cat logs.

"I parked my truck for 11 days at LAX and cats decided to sh*t and piss ALL over the sunroof," Rogan said.

"This is what was left after I drove 35 miles home. There was WAY more when I got into the car. Luckily it’s hot out so the sh*t was dry and hard, but f*ck is it disgusting."

There's more ...

"When I got in the car I was confused because it looked like someone poured a drink all over the windshield. We stopped at the exit and realized the entire top of the truck was covered with sh*t and piss."

So, what's the moral of the story ...