A guy fell asleep on the beach for several hours and got horrible sunburn, specifically to his upper legs. He went to hospital, and was promptly admitted after being diagnosed with second-degree burns..
With his skin already starting to blister, and the severe pain he was in, the doctor prescribed continuous intravenous feeding with saline, electrolytes, a sedative, and a Viagra pill every four hours.

The nurse was rather astounded and she asked "What good will Viagra do for him, Doctor?"

The doctor replied, "Absolutely nothing for his condition, but it'll keep the sheets off his legs!"