The line comes from the Ghostbusters theme written and performed by Ray Parker Jr. for the 1984 film, where the chorus repeats the call and response about not being afraid of ghosts. The song became inseparable from the franchise and its ghost catching team, playing over pop culture references for decades. Online, the short declaration was clipped on its own as a reaction sound for Halloween posts, gaming moments and horror comedy, keeping its meaning even without the full song, because almost everyone recognises the reference instantly.