My worst fall was about 5 years ago. I was in a lesson and riding a horse I was a little nervous to be jumping (the last time I had ridden her she took off bucking during a course - I somehow managed to stay on, but it scared me a little bit). Well we did the flat work part of the lesson and then everyone started to head to the jumping ring, I didn't want to jump so I asked if I could stay in the sand ring and do flat work. My coach said, no, you have to jump her. So into the jumping ring I go. The warm up jumps went fine, so then we started working over a line, small x, 2 strides, vertical, 1 stride vertical. Everyone went over and then it was my turn. I cantered her around the corner and pointed her at the line. Took the first jump long, I got left behind, lost my stirrup couldn't get back into rhythm with her, she chipped the second jump and hopped it, I was now on her neck - hanging on. Took the 3rd jump like a deer, I stayed on over the jump, but when she landed she did a crow hop because she was not pleased with the way I was flopping... I did a somersault and landed on my shoulder.
My coach made me ride her the next week too, but we did x's and trot poles. I wasnt comfortable riding her until a year later!
Most entertaining to watch:
Attempted to ride a cute little pony bareback.
Friend: going to use the mounting block?
Me: pfft, I don't need the mounting block, I can just jump on!
F: want me to hold him?
Me; nope. Im good.
Take Superman (mhm, that's right) into the middle, gather up the reins and jump on. Pony decides he doesnt like bareback and lays down
Ok, so its not a fall, but its an entertaining story.