Kim Kardashian & Saint West Toss Table on Kai Cenat in Live Stream Prank

Kim Kardashian and her son, Saint West, are teaming up on Kai Cenat ... helping hurl a table at him during a hilarious prank on his live stream.

The mother-son duo popped up on Cenat's "Mafiathon 3" -- a 30-day live stream that kicked off Monday night.

Kim walked in first ... wowing Cenat and his crew in a swanky white suit and fresh pair of shades. She hung out with them for about 30 minutes before jumping into Cenat's "Extreme Noodle Game" -- and that's when the fun really starts.

For those unfamiliar ... the game has players take turns sitting in a chair with a helmet on, while the others dance around them -- one delivers a smack with a pool noodle, and the person in the chair needs to guess who did it.

When it's Kim's turn to take a swing at one of Kai's buddies, she doesn't hold back ... winding up and whacking him on the head with a noodle! He immediately identifies Kim as the culprit.

But then ... it's Kai's turn in the chair, and his crew's got bigger plans than hitting with a noodle.

Kai's pal starts to lift a table with Kim's help -- and that's when Saint rushes in to join the team. Together, they hurl the table toward Kai, and it shatters on the ground. Kai quickly calls out Saint -- who's grinning ear to ear -- but Kim takes the blame.

The fun's not over yet ... as Saint plays a few rounds of the "Extreme Noodle Game" and strikes Kai in the head -- but when Kai pins him and says it's Saint's turn in the chair, Kim refuses to let it happen.