'We're Costco Guys' comes from the Costco Guys viral internet trend, which spread widely through short-form videos and reposted meme edits. The phrase became recognizable because of its enthusiastic delivery and its connection to big-box shopping jokes, family catchphrases and the 'boom boom boom' format. It stays popular because the clip is short, quotable and easy to drop into intros, remix edits and reaction posts. Online, it often appears alongside other goofy reaction sounds such as bruh when creators want a fast comedic switch.