Twice since I started seriously riding at age 13. Once while I was 15 and once when I was 21. Both times were at 4-way stops where I had the right of way and I went through the intersection and was T-Boned by the car on my left going through the stop sign.

I ended up on the hood of the cars both times. The incidents (they weren't accidents) were both eerily similar. No huge problems in either case, and the cars had larger bumps on their hoods than any damage done to me. In the first instance, my bike was completely OK. In the second, my front wheel and fork were damaged, but not the rest of the bike.