I tried to watch a movie about clocks.

The chuckle you just let out comes from a classic bit of wordplay, specifically a pun that hinges on a very common phrase. The brilliance of "about time" is its ability to mean two completely different things. Literally, a movie *about* clocks would indeed be a movie *about time*, as clocks are instruments that measure the passage of time. It's a straightforward description of the film's subject matter.

However, the real comedic punch lands when you hear "about time" as the familiar idiom, meaning something is long overdue or finally happening. It’s the kind of exasperated sigh or triumphant declaration you might make when something you've been waiting for finally occurs, like "It's about time you cleaned your room!" or "It's about time they released that sequel!" The joke cleverly exploits this dual meaning, making us anticipate one interpretation and then subverting it with the other.

This kind of linguistic gymnastics is a staple of comedy, taking everyday expressions and twisting them just enough to create an unexpected, delightful surprise. The humor comes from our brain quickly recognizing both meanings simultaneously and appreciating the cleverness of the linguistic switcheroo. It's a quick, smart joke that relies on our familiarity with common phrases to deliver a tiny burst of unexpected, pun-tastic humor.