Sunburns

Every summer (or any time I'm outside for more than 20 minutes, but we're just going to say summer so I don't cry), I get a "hilarious" sunburn. It doesn't matter that any time I think I may be exposed to direct sunlight I slather myself in 75+ SPF and put on long sleeves, the sun finds me and goes to town.
All this would be well and good if I would just do an allover sunburn that might eventually leave the residue pale-person tan that is really more red than brown but provides some color so pale people (like myself) rock it with pride. But my sunburns are tricky little minxes. Today, I am wearing the classic one-half-of-my-body sunburn. I was outside in a t-shirt and shorts today with all of my skin equally exposed to the sun. Somehow, only my left leg above the knee and right arm got sunburned. I don't understand why my body wants me to be ostracized from polite, tan society.
Another interesting sunburn fact that no one wants to know about me is that my shoulders are completely impervious to sun. I have intentionally let them stay out in the sun to try and get rid of the farmer burn that will inevitably last me for the rest of the school year, but no matter what I do, nothing happens to them. I am perpetually wearing little white cap sleeves.
If anyone knows of a cure for my sunburned woes, please send me a letter or something.