I tried to catch fog yesterday.

This joke is a classic example of wordplay, specifically a pun, which is the cornerstone of many one-liners. The humor hinges entirely on the double meaning of the word "mist." When you hear "I mist," your brain first processes it as a past tense verb meaning "to fail to catch" or "to miss." However, in the context of trying to catch fog, "mist" also refers to the atmospheric condition itself – a type of fog. The clever twist comes from the setup leading you to expect a failure, and the punchline delivering that failure while simultaneously using a word directly related to the very thing being pursued.

The visual of someone earnestly attempting to "catch" fog is inherently a bit silly, adding to the lightheartedness of the joke. Fog, by its very nature, is ephemeral and impossible to grasp, making the effort futile and thus setting the stage for the inevitable "miss." This combination of an absurd action and a perfectly executed linguistic trick makes the joke satisfyingly simple and effective, relying on the listener's quick recognition of the homophone to land the punch. It’s a clean, quick hit of comedic satisfaction that doesn't require much thought beyond appreciating the linguistic dexterity.