When you're feeling super good, like you are on top of the world, and some force, probably a stupid bitch, completely makes you do a 180 and start hatin' life.
Like The World Trade Center on 9/11/01. Thus, the term 9/11ed.
The conversation amongst you and you're friends might go something like:
-Dude, did you see that?
-Yeah, that bitch just shot you down.
- Man, I just got 9/11ed.
-Nigga, that was some straight second tower type shit.