The phrase "Roll Tide" is a cheer for the University of Alabama football team, known as the Crimson Tide. The color crimson refers to the jerseys the football players wear, and the phrase refers to the team rolling over its opponents.
The Alabama football team originally was referred to as the "Thin Red Line." That changed in 1907 when the team played a grudge match against rival Auburn University. Alabama played better than expected on a field that was covered in mud, and the game ended in a tie. The press christened the team the Crimson Tide, and the name has endured for generations.