It's the one that starts with "So as a joke, I went to my friend's house while wearing Konata's blue wig and uniform…"
So far, I've seen it go as far as Mar 1, 2012, but it was already spread around as a copypasta at that time. It's kind of a pointless endeavor, especially since it's a copypasta, but maybe some of you veterans know about it?
Also, would this be worth making a sub-entry for it? Not sure.