In PUA lingo, this is DHV (Demonstration of Higher Value). When someone wears something really outrageous it's like making a poker bluff saying "I am cool enough to get away with this outfit". They put that bet out there, and then the world can either call their bluff (by laughing at them), or if the world lets them get away with it, they have succeeded with the DHV.
Of course most people, like me, chicken out and don't even try to be outrageous. Wearing bland ordinary stuff is a way of being meek, invisible, of not trying, because you're afraid your bluff will fail and the world will laugh at you.