Doki doki is the Japanese onomatopoeia for a pounding heartbeat, long used in manga and anime to show excitement, embarrassment or nervousness. Sped-up edits like this one circulate on soundboards and short-form video as a shorthand for that feeling, because the faster tempo makes the reaction read instantly even without context. Creators reuse it for crush edits, reaction clips and comedic panic moments, keeping it popular as a quick, recognisable cue for a racing heart.