A time in the game where a referee is going to make a call and possibly stop play, but is waiting for the infraction, or one of the teams to touch the puck.
Often a slow whistle occurs during a delayed penalty when one team has committed an infraction of the rules and is not in possession of the puck, therefore the other team can continue on and try and score.
Other slow whistles occur on delayed offsides and potential icings when the linesman must wait to blow the whistle until the puck is touched.
During a `slow whistle`situation you will see one of the officials with non-whistle arm extended upright. This signals that a penalty will be called if it`s the referee and or a delayed offsides or icing situation if it`s one of the linesmen.