Sometimes I put my lid on back to front just to keep in with the “in crowd”. Unfortunately it’s an Arai race replica so it’s rather difficult to see out of. Keeps the back of my head nice and cool though.
Or breathe in.
This is the correct answer. It’s to keep the sun off their arms…and the pollution (and betelnut) off of their clothes. So the back is open to keep them cool while their front is covered giving their clothes and skin some protection from the smog.
P.S. funny one 21p, but you need to learn how to use the edit button.