In hockey, it is an informal word to describe a style of play where there are no penalties called. (Referee puts his whistle away...whatever)

In ice hockey, pertaining to the last few seconds of a very close game. It suggests that a team should engage in said rules to not let the other team win or score at all costs. Costs may include playing with extra intensity and engaging in illegal actions that would disable a player of the opposing team to make a play.