The ba-dum tss rimshot comes from live comedy drumming, where a drummer would punctuate a comedian's joke with a quick snare and cymbal hit. It became a familiar sound on stage, in sitcoms and cartoons, and later spread widely through online videos, memes and soundboards. Because the pattern is so short and instantly understood, it works even without context, signalling that a line was meant as a joke. That simplicity keeps it in regular use for reaction clips, edits and presentations.