A man fell asleep on the beach under the noonday  sun and suffered a severe  sunburn and heatstroke.

He was taken to the  hospital where his skin was  bright red, painful and starting to blister. Anything that touched him  caused agony.

The doctor attending him  prescribed continuous intravenous  feeding of water and electrolytes, a mild  sedative and Viagra.

"What good  will Viagra do him in that condition?" the nurse  inquired.

The doctor explained,  "It will keep the sheet off of him."