Muttley is the snickering dog from Hanna-Barbera animation, best known from Wacky Races and later Dastardly and Muttley in Their Flying Machines in the late 1960s. His wheezing laugh became one of those classic cartoon sounds that kept circulating far beyond the original shows. Online, creators use it as a quick reaction for sarcasm, trickery, and low-stakes villain energy, much like Nelson's HA-HA from The Simpsons or other iconic animated taunts.