I was mounting a horse I used to part-board, and as I was swinging my right leg over she stepped swiftly to the left, and I ended up flat on my back on the ground to the right of her. It knocked the wind out of me, and my friend, who was conveniently watching from a few feet away, burst out laughing (without bothering to ask if I was ok.. hmphhh). I was... just a tad embarassed. The mare just looked at me as if she was thinking, "Now what on earth are you doing down THERE??"