Grandpa: A grade school diploma. The one thing I've always wanted but never got.
Arnold: Couldn't you go back to school?
Grandpa: (Spit Take) Oh, I can't do that, Arnold. I'm too old. I've lost too many brain cells to make it through grade school.
Arnold: You're not too old, Grandpa. And you've still got plenty of brain cells.
Grandpa: No, not since Woodstock.
—Hey Arnold!, "Back to School"
