The phrase began as a short Vine clip in which a man films a dog and asks the question in disbelief, and the clip's blunt, funny wording helped it travel far beyond the original video. As Vine clips were reposted and remixed online, creators began pairing the audio with any dog caught doing something odd, turning a single moment into a reusable reaction. Its staying power comes from that flexibility: almost any unexpected pet behaviour fits the question, so it still works years after Vine itself disappeared.