Attack on Titan began as Hajime Isayama's manga in 2009 and became a hit anime in 2013, where Titans were defined as much by sound as by scale. Their bodies run impossibly hot, so wounds, regeneration and transformations are constantly accompanied by venting steam in the show. That distinctive hiss became shorthand among fans for a Titan moment, and short clips of it spread through anime edits, fan videos and soundboards. It remains popular because viewers recognise the reference instantly, even without seeing a Titan on screen.