Not a big fan of the "buttsecks" either. I think it'll be more appropriate for a parody fic warning. But, yeah, the fic loses credibility if the author uses “buttsecks” in the warning.
I really don't like links that lead to flocked posts. I mean, I'm a really lazy person, do I *really* have to friend you? And what if the story isn't what I thought it to be?
My only pet peeve with fic headers is when there isn’t enough information. I hate it when they don’t put a summary. But that’s just me.