Like Otters(열아홉 해달들)

Jae-Young Kim (played by Eun-Soo Shin), who secretly sells cigarettes through text messages at school and makes money, hides cigarettes in her desk drawer. During the exam, Seo Woo-gyu (played by Kim Jae-won) ended up sitting in Kim Jae-young's seat and was caught smoking by the teacher.