Since this morning Seo Yoon has been in an uncomfortable situation, he's been dying for poop. But there was no way he could ask permission for that in the middle of class, it would be too embarrassing for him. He tried to remain cool, putting both hands in his trouser pockets while sitting with his legs crossed. He started sweating coldly, every now and then his buttocks started shaking. "Oh shit! There are still 3 hours until rest. Anyway, I have to stay calm..." he said to himself."