Why are kids so mean?

Ok, whenever i'm in school, this kid and his friend bully me everyday. I barely know them...but their freshman's, and i'm a sopre, the other day in the boys locker room, one of the kids pushed me and jumped on me and held my arms to the floor, i couldn't move and he is stronger than me so when i tried to get up i couldn't. Then the other kid walked up and put his right on my face, then he started farting in my face, i tried to turn my head but he grabbed it and turned it so my nose was touching his as he was farting, i laid there as they did this for FIVE minutes, nobody did anything, i started crying and was coughing because it smelled really bad i wanted to hold my breath, they knew i hated what they were doing and they didnt care, i was grossed out and i couldn't take it. I couldn't move at all, they finally got off me, and told me i shouldn't be hungry anymore ? i don't know what they meant. How can i stop this and what did they mean ?