‘That’s the bee’s knees’ which means it is excellent, the highest quality.

The phrase ‘the bee’s knees’ came from the 18th century and it was a fanciful phrase that referred to something that didn’t exist.

A boss would send an apprentice to the store to pick up a left-handed hammer and a bag of bee’s knees.
In the Roaring Twenties in America, we added the bee’s knees to our nonsense language such as you’re the cat’s pajamas.

Some other expressions at that time included:

Kluck – dumb person.

Dumb kluck – worse than a kluck.

Pollywoppus – meaningless stuff.

Fly-paper – a guy who sticks around.

Do bees have knees? They do, they have six leg sections and each is connected by a joint. Call it a knee if you want.

Don’t confuse the bee’s knees with another early expression, the bee’s knee: that was a synonym for smallness, but it disappeared from the language.