The Catcher in the Rye by J.D. Salinger
When I was in grad school, I did an independent study class. The scheduling just wasn't working really well for me, so I created my own class about twentieth century American Literature. I created a reading list of book I hadn't ever read and asked my advising professor what he thought. The Catcher in the Rye made it onto my list, and his comment was "No. That book is only for 16 year old boys."
So I had still never read it.
He was right.
And as I was slogging through this 277-page novel, I was thinking "Um, how did this get named the great American novel?"
And then I thought of the scene from Despicable Me: "You call this literature?"