Unknown. One of many such informal phrases coined in the early 20th century for no apparent reason, of which only a few have endured. One possible origin is from the British expression "B's and E's" meaning "be all and end all". Another is a playful mispronunciation of business.
- (idiomatic, dated) Something excellent, outstanding.
- We had strawberry shortcake for breakfast on Saturday and the kids thought it was the bee’s knees.
- cat's meow
- cat's pajamas, cat's pyjamas
- cat's whiskers
- dog's bollocks
- the bomb
- the business
- (vulgar) the shit
- (vulgar) the tits
- Mark Israel, alt.usage.english FAQ
- Kevin Cook, Dubbel Dutch, Kemper Conseil Publishing, 2001, p. 222
- "Bee's knees" in Michael Quinion, Ballyhoo, Buckaroo, and Spuds, 2004.