loony bin

Insane asylum. The word “lunatic” comes from the word for “moon”; madness was associated in many cultures with the effect of the phases of the moon on the human mind. From lunatic came loony, and loony bin was where insane people were incarcerated. The phrase is now considered insulting in the extreme, as are “booby hatch” (originally a covered passageway down a ship deck), “funny farm,” “drool academy,” and “foam rubber city” (a reference to padded cells).