The calendar has nothing to do with it

I'm old. I'm not just not-young-any-more, I'm old.

People on my flist write and talk about "crack" fanfiction, and I just don't understand what that is, despite having gotten from one of them a definition once. I see self-defined "crack!fic" and I don't perceive any particular quality to seperate it from stuff I've been reading for thirty-five years.