Well, loving August 1963, to be specific, when Action Comics #303 hit the newsstands with this cover:
Apparently, Superman eats too much red kryupton (I hate when that happens) and turns into a monster: a giant, flying, limbless, knobby-skinned, fur-tufted snake with a unicorn horn. Yup. And to change back, Supergirl has to ride him. I don’t get it either. 1963.