I've had a few.
I was 12/13, my cousin an I decided(who were beginners at this point) to go for a trail ride on her brothers 17 hh green broke draft crosses. we were both 5', and the only tack belonged to her brothers, who were 6' + and all legs. there were no adults to help us. we tacked up and I got the hornless aussie saddle. Neither of us could properly tighten a cinch, so the saddles were a bit loose. the stirups didn't go short enough. so, riding horses that were poorly trained and loved to run, in loose saddles with no stirrups, we set out. we were in the middle of no where, on a quarter section that was completely wild and fenced for cattle. we ended up on a narrow game trail flanked by thick brush, when all of a sudden a bull moose came up behind us. in front of us a 4' high log had fallen across the trail. we had no choice but to jump it. I ended up with my arms and legs tightly wrapped around my horses neck. I pushed myself back into the saddle and we kept going. we got to a long, steep hill with thick brush at the bottom. that's when I found out the boys ran their horses down hill. racing flat out down a steep hill(with no horn or stirrups) I somehow stayed on, at the bottom I laid flat on my horses neck and clung for dear life as we crashed through the brush. And I survived to ride another day.
At 15: One on an interesting arab mare. incredible arena horse, but beyond spooky on the trail. We started out spooking at everything. then going down a wide trail there was a hub cap in the middle. instead of going around it like a sane horse, she jumped it unexpectedly, making me loose both stirrups and the reins, and galloping off towards the river. I stayed on, regained control, but now it was time for a river crossing. she fought me and fought me, before leaping 8' out into deep water
having survived thus far, we moved on to a nice wide trail that we usually cantered down. we had never seen anyone else on it. halfway down a man walked out of the bushes and stopped in the middle of the trail
our horses did fantastic sliding stops, depositing me and my friend in a heap at the guys feet, after having flown over the horses heads. the man took his girl friend and ran.
As an 18 year old: steep trail on a green horse, horse lunged up the last few feet, as I was leaning forward the horn hooked my bra. I ended up bent over a prancing horse, stuck to the saddle, trying to avoid plunging back down the hill. thus why I hate horns.
lastly, around the same time frame: we went to do a river crossing we had all done dozens of times, only this time flooding had washed out the bottom(water too dark to tell) we got 10' out from the bank and the bottom dropped out. out of 5 riders, 2 swam across, the rest of us swam our horses back to the closer side we had just come from. we were hanging off our horses letting them tow us back to shore when I heard this terrible screaming. I was sure my friend had been hit by her swimming horses hooves, or was being dragged under. then I heard what she was screaming. "My pants are falling off, my pants are falling off!!!!"
her fashionable low rise jeans were not coping very well with the situation
. then I tried to get back on the cantankerous gelding I was riding, but everytime I went to swing my(wet jean hampered) leg over, he would lunge up the hill, landing me in the dirt. I finally got on the brat, we found a way across, and my friend spent the rest of the ride trying to hold up her soggy jeans as we trotted the 7 miles home, looking like drowned rats
I have more, but these are a few.