Wedgies can cause testicular damage.

There is at least one reported case of testicular damage resulting from the popular schoolyard prank. Jack Watson, boy in Lincolnshire, England, nearly lost a testicle in 2004 when one of his friends at school gave him a wedgie. He was rushed to the hospital where doctors spent an hour reattaching his testicle to his scrotum. Afterward, he said that the wedgie still hurt.
(source)