Every time, I see a guy passing by wearing a pair of trousers/jeans like the ones on the picture bellow, I wonder:

Clothes worn next to the skin, beneath one's outer clothing. Also called underclothes, underclothing.

This means, that you should keep it beneath your pants, jeans or short pants. Easy and clear. ;-)

Now guys please, wear your pants properly!!! What's the fun about seeing their underwear?!... I don't get it but maybe it's because I'm from a different time.
Also, who on Earth thinks this looks nice?? Can someone explain?