Me: Okay, Papyrus. I'm no Sherlock Bones, but I'd say that Storyspin Sans is the Imposter.
Sherlock Bones
Explanation
Explain Bear
Listen up, buttercup. This joke is for intellectuals, but let me try. The user is pretending to be Sherlock Holmes (Sherlock Bones), but they make a skeleton pun while accusing the character Storyspin Sans of being an imposter.