Fat Kaiji refers to the character Polpo from JoJo's Bizarre Adventure Part 5: Golden Wind. He resembles the character Kaiji from the anime and manga of the same name, except very fat. This meme was originated in a small group watching of JoJo among friends but the joke quickly spread, most notably in the Discord servers of Twitter user @RealLeitungVG. The first known usage of the meme outside of a private voice call is a tweet from Twitter user @MadaoInTheSky, who first drew the comparison between Polpo and Kaiji.

This meme hit its high, however, when Twitter user @futchhina attempted to make a meme convincing people that incest is okay. This was brought to the attention of the Gang Weed Galleon, who swiftly replied to the tweet with nothing but an image of Fat Kaiji. This expanded as more people from outside joined in until over 430 images of Fat Kaiji had flooded the responses. This will surely grow, as Twitter account @BadAnimeTweets posted a screenshot of the post, and the replies to that tweet were also flooded with Fat Kaiji.