Cam Newton -- Xmas Bench Press Battle ... With Kevin Hart

Cam Newton called out Kevin Hart -- challenging the comic to bang out a set of 225 on the bench press ... AND KEVIN HART ANSWERED THE CALL!!

Cam, Kev and Ice Cube were at Harding High in North Carolina -- where they donated $7,500 for a new weight room -- when Cam put Kevin on the spot with the question that shook his manhood to the core ... how much can you bench, bro???

Cam started a "225" chant -- Kev asked Cube to hold his Santa hat -- and then it was on!!!