An NFL referee is responsible for overseeing the game and ensuring that all rules are followed. They are the head official on the field and are responsible for making final decisions on penalties, challenges, and other game-related issues. During the game, the referee wears a white hat and is positioned in the backfield, behind the quarterback.
When a referee throws his hat in the air after a touchdown, it usually means that a player who caught the ball went out of bounds before returning to the field and making the catch. The hat is thrown to mark the spot where the player went out of bounds. This is known as an "illegal touching" penalty, and it results in a loss of down and a five-yard penalty. The hat is used because the referee's flag is typically used to mark other penalties on the field.
One example of an NFL referee throwing his hat in the air after a touchdown occurred during a game between the Dallas Cowboys and the Minnesota Vikings in 2019. In the third quarter of the game, Cowboys quarterback Dak Prescott threw a pass to wide receiver Michael Gallup, who caught the ball and ran into the end zone for what appeared to be a touchdown. However, the referee threw his hat in the air, indicating that Gallup had gone out of bounds before making the catch. The play was reviewed, and it was determined that Gallup had indeed stepped out of bounds before making the catch, resulting in an "illegal touching" penalty and the loss of down for the Cowboys.