"Kek" is sort of the Korean version of "lol". In online gaming, Koreans made up a massive portion of Blizzard's early RTS game users (Starcraft and Warcraft), so much so that they put a nod to it in their mmorpg World of Warcraft, where it spread slowly as an english substitute for lol. After the meme wars of 2016 and 2017 it took on new meaning as among the gamers, shit posters, and meme lords as a battlecry against the media that declared war on a cartoon frog.