Lampshade Hanging

I came across the term "Lampshade Hanging" or "Lampshading" as a literary device in chapter 13 of The Kaiju Preservation Society by John Scalzi.  It comes up in conversation between two characters in the story:

"It's a reverse lampshade," I said.
"I don't know what 'lampshade' means here, much less its reverse."
"It's a literary term.  It means calling attention to something improbable in the text, and the moving on." 

I'm very happy to have learnt about a new literary term, and having two characters in a book talk about lampshading is in itself slightly messing with the fourth wall - which I also love.