The Hawks have been doing it after every home game for at least the last couple years.
The first time the Hawks did it was at a home game against Edmonton in December 2007. I was at the game, and the crowd was electric during the entire game. It was the first month in ages that the Hawks were seeing a sustained amount of high attendance numbers. The team congratulated the goalie and went to the dressing room. Moments later, the entire team came back onto the ice with sticks and pucks and threw them into the crowd. They did the center ice salute to the fans, who gave them a standing ovation. I got emotional over it.