Muttley is the snickering dog from Hanna-Barbera animation, most famously associated with Wacky Races and Dastardly and Muttley in Their Flying Machines in the late 1960s. His wheezy laugh became one of those instantly recognizable cartoon sounds that kept circulating far beyond the original shows. Online, creators use it as a shorthand for smugness, scheming and cheeky satisfaction. Its staying power comes from how quickly the laugh communicates a whole reaction without needing any spoken explanation.