Boomerang that Doesn't Return

Listen up, buttercup. So, you know how a boomerang is supposed to come back after you throw it? Well, this joke is about a boomerang that's a failure and doesn't do its one job. The punchline is that it's just a plain old stick if it doesn't return. The joke is funny, because it makes you expect the answer to be some kind of fancy wordplay with boomerang, but it is not! Get it now, smart guy? I bet you didn't know that a group of bears is called a sloth!