Univ. of Texas star defensive back B.J. Foster won't have full use of one of his hands for a bit ... his coach says he broke it punching his car in a fit of anger.
Tom Herman told reporters Thursday the junior came out to his vehicle in a parking lot ... and when he saw it had been hit (plus, the other driver didn't leave a note) -- he exploded.
"He got a little angry and decided he was going to take it out on the car bumper," Herman said.