On soundboards, short cartoon laughs are often filed by the character or feeling they suggest rather than by a single episode or scene, and this Heathcliff laugh is used in that loose, meme-first way. Creators search for it when they want a recognisable, feline-flavoured reaction that is quicker and cheekier than a human laugh track. It sits naturally alongside other animal reaction sounds, including the cat laugh meme, and keeps circulating because it is short, easy to recognise and easy to place at the end of a joke.