The line comes from Attack on Titan, the anime adaptation of Hajime Isayama's manga that began in 2013. Young Eren Yeager makes the vow after titans destroy his home and kill his mother, turning his grief into a mission to wipe them out completely. Clips of the delivery later spread on soundboards and in edits because the wording is simple, extreme and easy to apply to any grudge. It remains popular for exaggerated revenge setups where a minor loss is treated like a sworn vendetta.