The sound comes from the Harry Potter films, where the Sorting Hat places new Hogwarts students into one of four houses and announces the result aloud. Slytherin, founded by Salazar Slytherin, became linked in the stories with ambition, resourcefulness and a reputation for dark wizards. Fans clipped and stretched the house announcement into an exaggerated meme version, sharing it on soundboards and in edits whenever someone acts sly or self serving. Its continued use relies less on plot and more on instant recognition among Potter fans online today.