The ruler slap comes from Baldi's Basics in Education and Learning, the indie horror parody game released in 2018. In the game, Baldi uses ruler smacks as an audio cue that helps players judge his movement and distance. That mechanic made the sound memorable well beyond the game itself. It spread through gameplay videos, meme edits and short horror compilations, where creators use it as a fast signal for pursuit, pressure or an incoming threat, much like a FNAF Jumpscare Scream in quick reaction edits.