Michael Rooker's a pro when it comes to relaxing -- which turns out to be a slight problem while filming sentimental scenes with Chris Pratt.

We got Michael at LAX and he talked about the "Guardians of the Galaxy Vol. 2" blooper that's had fans cracking up. It's from his character Yondu's funeral scene, and since cameras couldn't show him breathing ... he had to chill himself out.

He pulled it off ... getting REAL chill, as in zonked out and snoring. Michael blames it all on his co-star, Chris, and told us it happened more than once. Or twice. 

Dude loves his sleep.