When someone pulls or yanks your underwear up and over your head.
At school, I still wore whitey tighties. No one knew about it because my shirt always covered it. But one day, when I took off my pants, someone accidently ran into me and everyone watching saw my underwear. Immediatly, the "boxer" people came over and pulled my whitey tighties up and over my head which became an atomic wedgie. My butt hurt like crazy! To make it better, they found duck-tape and tied me up and threw me in one of their lockers. They didn't let me out untill the end of PE class which lasted 45 minutes. It hurt!