The phrase comes from the Age of Empires series, where numbered chat taunts let players send short spoken lines to opponents during multiplayer matches. Blame your ISP fits that system perfectly, giving players a ready-made excuse when a game stuttered or a connection dropped. As old multiplayer clips, streams, and soundboards kept the taunt alive, it moved beyond its original matches and became a shorthand joke for any online lag. It still works because slow connections remain a universal frustration for gamers.