The phrase boi is a stylized spelling of boy that has circulated in meme culture for years as a playful way to call someone out. Clipped reaction lines like this spread through short form video, gaming clips and reposted soundboards because they are short, quotable and instantly understood without context. This version stays popular since the wording works for almost any baffling moment, from a bad decision to a strange visual gag, and it can be reused without needing the original scene or speaker.