What did josh do to his brother in the game? Why?

When he walked into the gym, he was covered in mud, everyone laughed, and JB viciously called him “Filthy McNasty.” Then, he was benched. Everyone cheered for JB as he made four three-pointers in a row. He saw JB wink at Miss Sweet Tea. Then, he was in the game and everything was like they practiced. However, as Coach and Dad screamed for Josh to pass, he thought of how he planned to pass to JB—but JB was calling him “Filthy” and calling for the ball, so he dribbled over to his brother and fired so hard that it leveled JB. JB fell to the ground, blood shooting from his nose.