Oh stop with the overexcited burkas are the next step comments.
It's about a simple generally acknowledged, albeit irrational, social norm that we all adhere to.
That is Underwear is not for public display.
It's nonsensical, as I would happily wear a bikini in front of friends on holiday by the pool but not my bra and pants in my kitchen with them at home.
Children can wear leotards to do gymnastics but not just their pants In The supermarkets.
Etc etc add your own example of our inconsistent, irrational but generally adhered to social norms regarding underwear.
One is : children should have their underwear covered when at school.
Not becuase it inspires lust in peados, not just because their girls, but just because its underwear which in that context is not socially acceptable, for girls or boys, and therefore makes people start to feel a bit uncomfortable. And even kids know this, that's why they snigger.
It's barmy but true. and Im sure most of you sad faced liberal hard liners on here adhere to this irrational inconsistent underwear norm most of the time.
If any of you are that naked walker guy I stand corrected and apologise.