When I was 11 at a family reunion at Bear Lake, I floated out on the lake on an air mattress and fell asleep facing downward. I was wearing a shirt so my back didn't get burned but the backs of my legs were burned so badly that I could barely walk for the following 3 days (one of my uncles attending the reunion was an MD and told my mom that the burns were more or less 2nd degree).
When I was 17 at a youth conference at Lake Lanier, Georgia, we spent the afternoon at a waterpark. This time, I didn't wear a shirt, and my chest, shoulders, and back were burned burgandy. For the rest of that youth conference and for a few days following it, I was utterly miserable (the worst was when the sunburn started to itch).
When BYU played UCLA in Provo in 1992, I sat in the middle of the north endzone and forgot to apply sunscreen to my face prior to the game. Came home only to find my face had turned purple. I think my nose and forehead must have peeled 3-4 times from that one.
A couple of years ago, I had a dermatologist check me out for skin cancer. Luckily, he didn't find anything suspicious. I should probably go in again (and regularly for the rest of my life).