David Foster Wallace was a genius & one hell of a fine writer. In his finest novel, Infinite Jest, he refers to a character having the “howling fantods”. I always assumed that fantods was a made up word, easily understandable through context.

Turns out, it’s not. It’s a real word, dating back to 1835:

There is an indescribable complaint, which will never allow a moment’s repose to mind or body; which nothing will satisfy—which allows of no beginning, and no ending—which wheels round the mind like a squirrel in its cage, ever moving, but still making no progress. It is called the Fantods.

Much more at the Grammarist.