What is the background of 'If you can't fight, wear a big hat'?

The way I've always taken it is :-   try to look tough, even if you're not.

You get insects that have the same sort of stripes as wasps but can't sting. It's a good defence so long as what is trying to eat you thinks that you can sting them.

A big hat will make you look taller than you are.


DC