and riddles.. whats under your hat and over your head?
(works best with kids.. and doesn't work at all with some adults.. especially males!)

The human body, when exposed to cold, conserves heat by diminishing blood flow to the exposed skin -- but for obvious reasons does not diminish blood flow to the head. Thus a great deal of heat would be lost from the head, and the species, though in general rather hairless, has evolved to retain insulating hair atop the head.

Unfortunately, some of us have lost much of that insulation as we age!

Oh, for the day when hats were fashionably acceptable!
[shivering -e]