Couldn't Help Myself

I was at the college picnic yesterday and I see a graduate student with a t-shirt that reads:
"Movies: Ruining Books Since 1930*"

I had to ask him, "have you studied marginal analysis?"

He was not familiar with the term, but he was the concept. He reminded me, accurately, that it is just a shirt for laughs.

*I can't remember the exact year.