It was kind of lame, I was riding in Central Park, up these rocks near Sheep's Meadow, I was clipped into my SPD pedals, started going up a steep incline of rocks, I was in the 32t chainring and 14t rear cog and wasn't able to pedal because it was too steep then all of a sudden I started rolling backwards, couldn't get my feet out of the pedals (damn clipless!) and then fell straight backwards onto my back.
Of course as I'm going down the only thing I was thinking was "Oh sh*t my bike is going to get scratched up!"
I was on the ground and some guy walking his dog was laughing at me. I was pretty embarassed. Surprisingly it was painless and my bike didn't hit the ground because I had it propped up with my legs.
I felt pretty stupid.