The joker acts as a 'wild card' that can transform into any other card. Because of this, it has come to mean an unpredictable person or variable that can change the outcome of a situation, even outside of a game.

It became an icon of pop culture symbolizing chaos and unpredictability, especially after gaining fame as a villain in the Batman series. So, it's sometimes used with complex meanings beyond a simple joke, like a powerful being that can upend a situation or a dark hero.