“Actor and comedian, Marty Feldman (below), from Young Frankenstein was the definition of swivel-eyed.”
Swivel-eyed
Definition (adjective) chiefly British slang: having extreme, deranged, or fanatical views “He is a swivel-eyed fanatic”; “They are a bunch of swivel-eyed loons”.
Pronunciation: swiv-uhl-ighd