When we got to Wellpint, some kids lined up and started throwing snowballs at the bus, and some had rocks in it.
As I run out into the court someone goes and throws a quarter at me. And it hits me in the fricken head.... It needed 2 stitches.
This happens in the beginning of the chapter when Junior is so nervous about the game that he throws up from anxiety. He got so stressed and worked up about how he was going to be mad fun of at the rez that he physically gets sick, poor kid.
This happens at the middle point of the chapter when the Reardan team arrives at the Wellpint high school at the rez to have a basketball game. The Indian's show their discontent by throwing snowballs with rocks at the bus containing Junior and the team the team.
This is the middle to end of the story when Junior is out on the court playing and a member of the crowd on the Wellpint side with 20 20 aim throws a quarter and hits Junior in the middle of the forehead making him need 2 or 3 stitches. This makes it clear that the Wellpint people don't just hate Arnold or Junior they despise him enough to seriously harm him.