Australian rules football
Every game consists of 4 quarters, being 20 minutes and overtime (stoppage time, time-keepers acting upon central umpire signals to determine how long). After every quarter the teams swap direction. The quarter is started when the umpire blows his whistle and bounces the ball in the middle of the field (similar to a basketball "tip")and opposing players try to tap or punch the ball to their team-mates.