The origin of this ei clip is not documented, so it circulates online mainly as a tiny standalone reaction sound shared on soundboards. Its title uses the bopomofo character for the ei syllable, which explains the short, vowel led pronunciation listeners hear. Because the file is only a fraction of a second long, editors treat it as punctuation rather than dialogue, dropping it into memes, short videos and chat audio where a longer voice line would slow the joke down or crowd out other sounds in the mix.