911 attack. I was sleeping on the couch at a friend's place and he was apparently awake gaming online (yes that was already a thing in 2001). He came into the living room and apologized for waking me up but he wanted to turn on the TV because someone on the game server had said there had been an "incident". This was a few minutes before the 2nd WTC plane hit. So it wasn't yet clearly a terrorist attack. Ended up watching the coverage all day.