The phrase comes from the standard greeting used by 911 dispatchers in the United States, where 911 has been the universal emergency number since the late 1960s. Callers expect the question what's your emergency as the first line of any real call, which is why a short, cut off version became popular on soundboards. Shared as a meme setup, it lets creators borrow the authority of a real emergency call for jokes, roleplays and edited phone conversations where the reported problem is anything but urgent.