Icing

Icing is a violation called when a team shoots the puck from its own half across the opponent's goal line untouched, stopping play with the faceoff coming back to the offending team's zone. It exists to stop teams from simply flinging the puck the length of the rink to relieve pressure. The tired-legs penalty is real: the offending team cannot change its skaters, so a bad icing can trap an exhausted line on the ice for a dangerous defensive faceoff. The rule is explained in USA Hockey's rulebook.