In what way are so-called "ironic" t-shirts, gles, etc actually ironic?

I share your confusion. I have a friend who wears those ridiculous plastic Kanye-West style gles, and he claims he wears them ironically. Who is getting the joke? I think people want to wear these things but are too afraid to be judged, so they put up a front to protect themselves. It's weakness, and it's moronic. There is nothing ironic about wearing a pair of plastic gles.