Jevil is the secret jester boss from Deltarune Chapter 1, released in 2018 as the follow-up to Undertale by Toby Fox. Players find him locked in a cell in Card Kingdom, and his manic laugh became one of his most recognisable traits alongside his chaotic boss fight. Clips of the laugh spread through YouTube edits, TikTok videos, and Deltarune soundboards, where fans reuse it to signal madness, trickery, or a sudden twist. It remains popular because it is instantly recognisable to Deltarune fans and works as a short, punchy reaction even outside the game.