Vai dormir is everyday Portuguese for go to sleep, while oxi is a shortened form of oxente, a common Northeastern Brazilian expression of surprise or emphasis. Combined as a shouted catchphrase, the line spread through Brazilian WhatsApp groups, short videos and soundboards as a reusable bedtime joke rather than a quote from a single known show or film. Its appeal comes from that familiar mix of affection and exasperation, so it keeps circulating whenever late-night chats, livestreams and gaming sessions run longer than they should.