The Fifth Down

In 1990, the Colorado Buffaloes, a college football team, had a game against the Missouri Tigers and showed up late to the game. On their final drive, the Buffaloes marched down inside the Tigers' five-yard line. After a fourth down run attempt failed, the ball should have gone to the Tigers. However, the Buffaloes quickly lined up, snapped the ball and scored the game-winning touchdown.

Later it was revealed that the down card was never flipped, while the officials discussed whether the Buffaloes had scored on the previous play. This game is nowadays commonly referred to as the Fifth Down.