I think the oil you baste your turkey with is a lot hotter than your head in the sunshine. I've found that being in the sun with an oily head is akin to doing a hot oil treatment: my hair just comes out soft and shiny, sometimes overconditioned-fluffy. Maybe it helps to be popping in and out of the water.

I don't know, but I don't think it's uncommon to put oil in your hair to keep the sun and saltwater from drying it out.