With 2:49 minutes left to the game, Boston Bruins' goaltender Tuukka Rask bought some time for his teammates who just iced the puck and were about to take a faceoff in their defensive zone: he flipped the net over. You read it right, he flipped it over.
The referees had to replace the net before resuming the play which got his team at least 20 seconds to get their breath. Did the referees gave Rask a penalty? Nope. Now was it legal? We're not a 100% sure.
Here's the ruling that should have applied and see for yourself:
63.2 Minor Penalty - [...]. A minor penalty shall be imposed on any player who delays the game by deliberately displacing a goal post from its normal position. The Referee shall stop play immediately when the offending team gains control of the puck.