The phrase comes from SimCity 2000, the 1993 city-building game, where it appeared among the playful messages shown while a city loaded. Reticulating splines was never a real technical step; it was invented jargon that sounded plausible enough to make waiting feel productive. Players remembered it long after the game, and clips of the line later circulated online as shorthand for any slow, mysterious or pretend-technical process. Its lasting appeal comes from that mix of nostalgia, fake authority and the shared joke that something important is supposedly happening behind the scenes.