Mother of All Stories You Don't Quite Believe at First

I was working in an office (story of my life) on the morning of September 11, 2001. I had gone out for breakfast for the whole group -- it was my turn, or I was the hungriest of the bunch. Normally, breakfast errands were risky -- we weren't allowed to leave the building except on approved errands, and we weren't supposed to eat or drink at our desks. We occasionally risked it, but this time, the boss was out of the country, and I was in the car listening to the radio and thinking about an egg sandwich. I pictured a small plane with mechanical trouble, or a pilot with serious DUI (FUI?) issues, but at some point, maybe when the second plane hit, it became obvious that it was not an accident.

Perhaps the mother of ASYDQBF for a previous generation was The War of the Worlds broadcast, but that was fictional, although it caused quite a panic at the time. (See especially the report of people shooting at a water tower, thinking it was a flying saucer.) The War of the Worlds broadcast was part of the reason that people did not, apparently, immediately believe the news of the attack on Pearl Harbor three years later. (Source, Wikipedia, op. cit.)