Bankai comes from Bleach, the manga and anime series created by Tite Kubo, where it is the second and most powerful release of a Soul Reaper's Zanpakuto sword. Fans have used the word online for years as shorthand for any over-the-top power-up, which made it natural meme material. Pairing the call with a simple wow reaction turned a serious battle moment into a flexible reaction sound, and short clips like this one spread through anime edits, gaming videos and soundboards where a two-second power-up punchline is needed.