Today in 1825, Eli Whitney, known for inventing the cotton gin, died. How is this related to the idiom having a “screw loose”? I’ll tell you.
According to dictionary.com, it’s defined as slang, meaning “to be eccentric or neurotic; have crazy ideas: ‘You must have a screw loose to keep so many cats’.”
I remember reading that the origin of the expression comes from the cotton gin, or certainly from the time of the Industrial Revolution, when apparently the device wasn’t made well and screws kept coming loose, causing big problems with the mass production the device was supposed to encourage. As a result, any time something didn’t work well (originally in regards to the textile industry), or came out crooked, it was referred to as having a screw loose.