What do you call a boomerang that won't come back?

This joke plays on a delightful bit of anti-humor, relying on the audience's ingrained understanding of what a boomerang is supposed to do. The humor mechanism here is a subversion of expectation, combined with a literal interpretation. We expect a clever, perhaps punny, answer related to its returning nature. Instead, the punchline strips the object of its defining characteristic, reducing it to its most basic, non-functional form: just a plain old stick. It's funny because it defies the very essence of "boomerang-ness."

Historically, boomerangs are fascinating tools, most famously associated with Indigenous Australians, who used them for hunting, sport, and ceremonies. While many people think all boomerangs return, non-returning throwing sticks were also used for hunting larger game like kangaroos and emus, optimized for distance and impact rather than coming back. The returning boomerang, however, is a marvel of aerodynamics, designed with specific airfoil shapes and angles that allow it to spin and curve back to the thrower. In fact, boomerangs have been found in various cultures across the globe, with some ancient examples dating back tens of thousands of years, even including a collection owned by King Tutankhamun.

So, the humor hinges on our collective knowledge of this unique, returning projectile. When it fails at its one job, it's no longer special; it's just a piece of wood. It's a simple, elegant joke that gets a chuckle by taking away the very thing that makes a boomerang, well, a boomerang.