There is no shortage of complaining to the officials in an NBA game.
But this year is the first time coaches can do something about it if they think an official has erred.
The league has been experimenting with a new coach's challenge in which three types of calls are up for review — fouls, out of bounds and goaltending/basket interference. Like the NFL and its red challenge flag, coaches have to signal when they want a challenge by calling a timeout and then waving their index finger in the air, which then sets off a little green light near the bench indicating a challenge is in progress.