before you can say knife

== English == === Etymology === (This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.) === Phrase === before you can say knife Very quickly; quicker than one expects. Synonym: before you can say Jack Robinson ==== Translations ==== === Further reading === “before you can say knife”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022. “before you can say knife” in Idioms and phrases, TheFreeDictionary.com, Huntingdon Valley, Pa.: Farlex, Inc., 2003–2026.