So, I'm going to start out and explain the situation and I'd like to know what you think should have been done!
I, more or less, free lease a gelding named Jasper who is about 11 years old. I've started him under saddle about 5 months ago. Everything went well, no bucking or anything like that. The owners have three girls that would like to ride him some day, but they don't come out to the barn much.
Well, I was at the barn riding Jasper bareback(this sunday) and they came and wanted to ride. I let the two that had come a turn each to ride and lead them around(I gave them my helmet). Jasper wasn't thrilled(I've been the only one to ride him till then) but he put up with it fine. Once they were done I hopped on and was going to ride back down to the the little barn where he's pastured, when the older of the two girls(she's about 7 but tall for her age) wanted to ride back with me, so I said ok and figured Jasper would be fine. She got on behind me then Jasper starts side stepping, I tried to stop him and then, bang, he turned into a bucking bronco. There was no way I was staying on bareback with a girl trying to hold on to me, we ended up slipping not so gracefully off. We were both fine, it wasn't that far down, though the girl cried till they left 5 minutes later.
So, down to the the question, what would you have done in this situation when the horse started bucking? To start with, I do realize I probably shouldn't have let the girl up with me, but what would have been the best thing to do considering there was another rider with you and your horse starts to buck or misbehave?