...you are on a medication that you are unaware that it makes you sensitive to the sun
...you normally dont burn so you aren't wearing sunscreen
...you ride on the back of a harley for 120 miles under mostly cloudy skies with a low cut tank top to look like all the other biker chicks
...you end up sunburned so bad that it gets into layers of skin causing blistering. When it peels it doesn't just take the top layer of skin with it...it goes several layers deep...and bleeds....and hurts...I have what you use on burns that is a gel that becomes a protective second skin on it. it feels like any sudden movements and the entire area will rip off again.
ALWAYS wear sunscreen
Know your medications if they make you sun sensitive let your doctor know.
Wear a t-shirt if you are going to be in the sun for extended periods so sensitive areas aren't burned.