The joke works because Sheldon Cooper is widely recognised as the famously logical, socially awkward genius from The Big Bang Theory, so calling him you dog flips that buttoned-up image into playful praise. The clip circulates online as a short reaction sound, shared in edits and memes rather than as a longer scene, and its two-second length makes it easy to drop over a win, a comeback or a cheeky moment. That contrast between the nerdy name and the streetwise compliment is why creators keep reaching for it.