yup. was going about 35-40 down a hill. Bike slid on grave and I hit a huge rock in the middle of the road. Did a front flip bounced on my hip and then landed on my head. Was blacked out for a couple minutes.
My helmet saved my life, but my hip was badly hurt. Didn't tell my parents so I had to live with the pain for two weeks. I could barely walk without screaming for the first couple days.