Nonce

From Wakefield Prison in England, NONCE or; Not On Normal Court Exercise, means a prisoner is not on regular exercise times with other prisoners, due to their offences being of a sexual nature and involving minors. This acronym became a slang insult in the United Kingdom to mean someone who is attracted sexually to minors.

"Hey Geoff, did you see the news?"
"Yeah, Jimmy Saville is a nonce? I could have told you that years ago."