17 possible answers to
Answers with 3 characters: MAD NUT Answers with 4 characters: BATS DAFT LOCO NUTS Answers with 5 characters: DOTTY BARMY NUTSO WACKO Answers with 6 characters: INSANE MADMAN PSYCHO WEIRDO Answers with 7 characters: NUTCASE Answers with 13 characters: AROUNDTHEBEND Answers with 15 characters: MADASAMARCHHARE