Well ... it took his new Atlanta Hawks teammates only a few months to kill his chill -- 'cause they JUST STUFFED IT WITH A BOATLOAD OF POPCORN!!!

Jeremy Lin documented it all on social media ... showing the Atlanta rookie's new custom Audi R8 packed to the brim with the buttery stuff.

Trae wasn't the only victim Friday ... fellow rookie Omari Spellman had his (far less expensive) whip filled with the kernels too!!

At least it wasn't your average stale popcorn ... Lin performed a taste test and said, "That's high-level popcorn!"

The rooks seemed to take it in stride ... which is good news for the Hawks vets -- 'cause these pranks don't always go over so smoothly.

Kenyon Martin once threatened to kick the crap outta whoever stuffed his ride with popcorn in 2010 ... and Jaylen Brown told us just a few months ago he's STILL out for revenge on Amir Johnson for the prank.