toodle-oo

First recorded in 1905–10; of disputed origin; perhaps an elaboration of toot ¹( def ); perhaps toodle (variant of dialectal tootle “to toddle”; toddle ( def ) ) + -oo, interjection; perhaps a corruption of French à tout à l'heure “see you later,” literally, “to everything at the hour” ( à la ( def ), tout ensemble ( def ), hour ( def ) )