include: Running out of bounds with the ball. In the NFL, this only stops the clock in the final two minutes of the first half and final five minutes of the second half; the rest of the time, the clock stops only temporarily, restarting when the ball is set for the next play. In arena football, the clock stops only for out-of-bounds plays in the final minute of the half. Throwing the ball out of bounds. This is an incomplete pass, and depending on the circumstances risks incurring an intentional grounding penalty, but sometimes, the team may choose to sacrifice a down to stop the clock. Spiking the ball. This act, likewise, is an incomplete pass and sacrifices a down, but when performed immediately after the snap is explicitly permitted without the risk of incurring an intentional grounding penalty. Waiting for the two-minute warning in the NFL, three-minute warning in Canadian football, one-minute warning in Arena football if it is approaching. College and high school football do not have any of these stoppages. Committing an offense for which a minor penalty may be called. In some leagues, late in the game, a 10-second runoff is assessed to discourage such tactics. Feigning the injury of a player. If this occurs more than once in a game, a timeout may be charged, and/or a penalty may be assessed. In some leagues, if time is called because of an injury, the injured player may be ordered to sit out at least the next play as a way of discouraging the feigning of injury. In the NFL, college football, and CFL, a timeout is assessed against a team if a head coach unsuccessfully challenges a play. A common practice in gridiron football is to call a timeout right before a potential game-winning or game-tying field goal, a strategy known as "icing the kicker". In theory, this strategy is based on the presumption that the kicker has prepared himself mentally to make the kick only to have the timeout break his concentration. While this strategy has seemingly worked on occasion, statistics suggest that not only is this an ineffective strategy, but is actually counterproductive because kickers are more likely to make a field goal after a timeout is called—possibly because they have come to expect a timeout to be called, if the opposing team still has one. There have also been times when the tactic