You should tell that to your own Panthers. Their defense has a policy to not allow the opposing team to ever celebrate a 1st down. In fact, in the Superbowl, one of their players was flagged for unsportsmanlike conduct for doing his. He slapped the ball out of the hand of a Bronco who was celebrating after a catch. Don’t believe me? Read it for yourself:

http://www.charlotteobserver.com/sports/nfl/carolina-panthers/article55903670.html