To add to u/annamaga 's first link, the article describes "kek" as a Korean onomatopoeia and barely mentions then completely dismisses the World of Warcraft origin.

World of Warcraft sees two factions warring against each other: the Alliance and the Horde. It turns out that when one faction speaks a language not understood by other characters, a destructive word scrambler is used such that each faction knows a character said something but the original words can't be deciphered for the faction it wasn't meant for. All Alliance-aligned characters can speak the "Common" language, all Horde-aligned characters can speak the "Orcish" language, in contrast to race-specific languages within each faction.

Thus, the word "lol" spoken in the Orcish language can be read as "kek" by the Alliance-aligned characters. Sometimes the inverse operation is possible, and this is the case here: the word "kek" spoken in the Common language is read back as "lol" by the Horde-aligned characters, leading to the popularization of the use of the word "kek" by players, then bleeding out of the game and into adjacent cultures.