I remember the first time my little sister went to a swimming pool with my father, who by that stage was very thin on top but still had a Sean Conneryesque thatch of hair on his chest. He walked to the side of the pool, and my sister said, very loudly, 'Daddy, that's where all your hair's gone!'
I struggle with the logic that it rapidly fucks off from the top of my head and reappears elsewhere.