NHL fans have every right to protest.
Boston Bruins supporters, for example, performed their civic duty on the second-to-last day of the season, mercilessly booing their team in the fading moments of a 6-1 loss to the Ottawa Senators. It was a fitting response to the lethal blow in what was a pain-staking, month-long collapse.
Upset in their own right Monday, Flyers fans had similar intentions when the home side, clearly outmatched in their first-round series with the Washington Capitals, saw a third straight game - and really, the series - slip away.
It was innocent enough to start. Audible restlessness, smatterings of boos. That was until it wasn't.
Excited perhaps by Pierre-Edouard Bellemare driving Dmitry Orlov into the endboards from behind, or Radko Gudas taking the opportunity to throw punches at an opponent three or four weight classes below his, or because they just didn't want to see a Capitals power play - which scored five goals with the extra man in the game - go to work again, they stepped over the line.
After Alex Ovechkin's 5-1 goal and after warnings and pleas from the PA announcer, Flyers fans littered the ice with light-up bracelets given out to honor late owner Ed Snider. One of them even hit Orlov in the face as the trainer worked to clean up the abrasions from Bellemare.
It was an embarrassing night for the Flyers organization and a horrible look for the league, which had two of the more important franchises on national air.
But in truth, this isn't anything new - there's a long history of fans misbehaving in the NHL.
Domi's dust up
This Flyers fan didn't step over the line, he toppled over it.
Chris Falcone's infamous dust up with former Toronto Maple Leafs enforcer Tie Domi is, for better or worse, one of the more memorable fan moments in the league's history.
Vancouver riot
While the Bruins celebrated with the Stanley Cup inside the arena, the streets of Vancouver burned on the outside.
There were more than 100 injuries, more than 100 arrests, more than 300 people charged, and countless vehicles flipped when a riot broke out in the streets of Vancouver after the Canucks' Game 7 loss to Boston in the 2011 Stanley Cup Final.
The estimated cost to clean up the damage was at $4 million-$5 million.
Asselstine decks fan
Former linesman Ron Asselstine did his best to help discourage future fan runners, blasting an intruder in a 1989 game at the Boston Garden.
Waffle toss
Catharsis by way of waffle.
Maple Leafs fans showed their frustration in a unique way during the team's third straight last-place finish in the 2009-10 season, chucking frozen breakfast treats onto the ice.
Richard Riot
In 1955, there was a riot in the Montreal Forum when former NHL president Clarence Campbell showed face at a Canadiens game after suspending Maurice "Rocket" Richard for the remainder of the season.
He was pelted with food and debris and physically assaulted before a tear gas bomb was set off in the arena, forcing an evacuation.
