What film or novel would you be most surprised that a friend had not seen or read?
I have to admit I am always very surprised when someone in RPG circles tells me they have never read J.R.R. Tolkien.
To me it is so integral to what I consider my own RPG experience.
Now I am not surprised when I hear people have not read H.P. Lovecraft. I find that more people talk about his works than have actually read them.
For movies. I am in shock when I hear that someone has never seen Star Wars. That is also so central to my own RPG upbringing.