The bee's knees

The bee's knees. Now that's an interesting saying isn't it? It seems there's no definitive explanation as to when or how it evolved.

I like this explanation though:

"There's no profound reason to relate bees and knees other than the jaunty-sounding rhyme. In the 1920s it was fashionable to use nonsense terms to denote excellence - 'the snake's hips', 'the kipper's knickers', 'the cat's pyjamas/whiskers', 'the monkey's eyebrows' and so on."

This could be the start of a wee series - today we have the bee's knees, tomorrow maybe the cat's pyjamas. Anyone got any kipper's knickers I could borrow?