Inane in the Membrane

For no reason whatsoever, I recently found myself repeating four words that sound nonsensical, which is appropriate, because they connote idiocy.

Pell mell.

Harum scarum.

Willy-nilly.

Helter-skelter.

I'm a word nerd, a grammar geek, a usage unicorn. Wait, that last one doesn't make sense. I love using obsolete or obscure words and phrases, such as "What the deuce!" and "satchel." So as I repeated the four words above, I realized I needed to know more about them. So on, then, to the Merriam-We...