I was introducing a 4 year old to trotting poles - WALKING - and she decided to bend down, sniff, raise one leg to step over...(by this point I was STUPIDLY looking down watch what she was doing while pushing her on)...and then cat leaped 4 feet in the air over it!
Next thing I know I'm on the ground, covered in sand and the little mare is looking at me with big wide eyes and a 'whatcha doing down there?' expression.
At least there were onyl 2 people watching.
I also lost a stirrup during a canter circle in a GROUP lesson once and ended up coming off. BUT I turned it into a running dismount
I landed running, without moving my hands from the pommel of the saddle, and pulled the horse up from the ground. Embarrassing, but I was quite pround of me. Clearly I should have done gymkana as a kid - if only I could remember how I did it!