One time, at band camp...
Seriously, at an enduro, I think it was Lubbock Trail Riders, I slammed a rock at the bottom of a downhill going into a creek. It bent the rim on one side and pinched the tube (didn't find that out until the tire went flat about 10 miles later). The hit was pretty hard as all I heard was a big "BANG" and jolted my whole body. The bike never even wandered on the trail and I didn't really give it much thought at the time.
Not sure if this is what you are looking for. Let's just say the hit was pretty hard on a rock that was sticking out at an angle.
DTSViper