Why did the horse get bad grades in school?

This joke trots out a classic example of wordplay, specifically a pun. The humor hinges on the phrase "horsing around," which has two distinct meanings. On one hoof, it literally describes what a horse (Review) does – running, playing, and generally being a horse. On the other, and this is where the punchline bucks up the laughter, "horsing around" is an idiom we use for people who are being silly, mischievous, or not taking things seriously, often to the detriment of their responsibilities, like schoolwork.

The joke cleverly sets up the expectation of a typical school problem, then delivers a punchline that's both literally true for a horse and figuratively true for a student slacking off. The absurdity of a horse attending school adds to the lighthearted fun, allowing us to chuckle at the image while appreciating the linguistic trickery. It's a simple, clean joke that relies on our familiarity with common idioms and our ability to connect a literal animal action with a human behavior.