According to a West Newbury Police Department report excerpted here, an officer was called to the school and observed a 32-ounce Gatorade bottle that was a little over a 1/4 to a 1/2 empty and noted that the liquid appeared to be lighter in color than most Gatorade products. After smelling the contents police determined that it had some sort of alcohol added to it and a test of the liquid determined alcohol present in the container.
They drank her booze.