Kristin Cavallari may have slept with a major movie star ... 'cause her friend shouted out she and Jason Statham hooked up in a viral video trend.

Here's the deal ... Kristin Cavallari and her longtime pal Justin Anderson participated in the "Suspect" trend on social media -- the video trend where friends yell out "Suspect is..." followed by brutally honest, often hilarious facts, about one another.

Kristin and Justin's is no different ... with the two trading barbs -- including one where Justin says "Suspect's hottest hookup that she's never told anyone about was with Jason Statham."

Pretty cut and dry here ... Justin's saying Kristin and Jason did the deed -- though, to be fair, he yells it out during a video trend that's supposed to be funny.

Worth noting though ... Kristin and Jason were romantically linked way back in the day -- before she even married Jay Cutler -- so, it's not outside the realm of possibility.

Speaking of Cutler, Anderson seemingly fired a shot at the former Bears QB in the clip too ... saying Kristin has "turned all of her ex-boyfriends into alcoholics." Remember, Cutler was arrested just last month on DUI and gun charges.