Jayson Tatum is a straight-up savage ... the Boston Celtics star forward showed no mercy towards his little son, Deuce, rejecting his shot in a hilarious video!!
Tatum was hosting a youth basketball camp at his old high school, Chaminade College Preparatory School, in Missouri ... when he taught his 4-year-old son a hoops lesson the hard way.
In the clip, Deuce drives to the basket with dad trailing (that's traveling everywhere but the NBA). He stops, collects himself, and puts up a J ... when Tatum sends his shot flying!