I initially thought you automatically got one at 10,000 posts.
I was then hanging around 20,000 posts (I think) before asking what was up. I mentioned that perhaps I'm not interesting enough to be worthy of one and then well, there you go.
i was on late one night a long time ago and someone commented about a photoshop i had done, and mat challenged me to shop something. i did (not even a vague recollection of what it was), and bam...
got changed to two lines as to not **** up threads, but was one line.