What does "the bee's knees" mean — and why is it funny?

informal, playful

Meaning

Something or someone excellent — first-rate, the very best.

Where it comes from

A piece of playful 1920s slang, coined in an era that loved inventing silly animal-anatomy phrases to mean 'excellent'.

Why it is funny

The humor is pure nonsense. A bee's knees are not impressive, or even really visible — the phrase was invented precisely because it sounds cheerful and means nothing, and saying it still feels like a small wink.

Used in a sentence

"She thinks her new haircut is the bee's knees."