1. The phrase "wear it" originated with a meaning relating to humiliation. If someone did something humiliating or was humiliated in some way, they were "wearing it" or could be told to "wear it."
2. The phrase progressed to have a meaning related to drinking. A person is "wearing it" when they are either very drunk or hung over.

Literally everyone, ever. Including the writer of this definition.

expression said to someone when they fall or do something stupid to make them feel worthless

To "wear it" is is to be publicly humiliated and do nothing about it.

Pretty much the money shot, after some one has finished on another, hence, Fuck You.