Yes, I have. I learnt about sunburn the hard way; it is most unpleasant. I had blithely spent a quiet summer afternoon in the buff by the seaside, without taking any sunblock. I certainly regretted that towards the evening. The only thing that helped was covering myself in cold, wet towels and nothing else. After a day or two, the dead skin came peeling off me. I now never go anywhere without sunscreen when the sun is out. When I am wearing short sleeves in the sunshine, an hour is amply sufficient for turning my arms red and itchy. Even my hands get irritated very quickly.