This sound comes from the animated television series Rick and Morty, which premiered in 2013. Short reaction clips from the show spread widely through meme edits, repost pages, and soundboard-style sharing because the voices are recognizable and the timing is easy to drop into videos. The phrase "I'm in" stays popular because it is simple, flexible, and instantly communicates commitment, whether the joke is about bad decisions, hype, or going along with an absurd scheme.