Addicted (2016)

Gu Hai gets two sleeping pills from the school's doctor and puts them into Luo Yin's water bottle. Unfortunately, the cold medicine Luo Yin took in the morning is expired and that combines with the sleeping pills knocks him out unconscious in class. The next day, some jealous brat from another class , Wu Fang, barges in the classroom and starts insulting Luo Yin's mom, calling her a prostitute. Enraged, Gu Hai knocks Wu Fang down and starts beating him up.