Banana

A simple single-wire plug with a springy banana-shaped body, used for hi-fi speaker terminals and lab/test equipment. Push it into a binding post and it grips.

The sprung "banana" curve is the whole trick, it flexes to grip the socket walls and hold a solid contact.

Mind polarity (red +, black −) and avoid them where shrouded mains-safe terminals are required.

Almost a century old and still the tidiest way to wire a loudspeaker. Sometimes the simplest mechanism is the one that lasts.