Bee-s-knees Definition

noun

(idiomatic, dated, usually with the) Something or someone excellent, outstanding.

We had strawberry shortcake for breakfast on Saturday and the kids thought it was the bee's knees.

I used to play in a band when I was younger. We had a few fans and we thought we were the bee's knees.

There is a new bee's knees every few minutes in New York.

Wiktionary

Origin of Bee-s-knees

Unknown, with reduplication. 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.

From Wiktionary
First known use: 1922.

From Wiktionary