Social Media 101 says no one will read your posts unless there are completely unrelated pictures next to it.
That's funny. I read the first one, then all I did was look at the photos. I understand that I'm just me but this article was more set up as a number of photos with some unrelated SQL tips around it. I think the poster over did it. I think the Social Media 101 is more referring to how Joel used to add a bit of flair to his articles.
Most likely a bug due to MySQL handling NULL's strangely.
As another comment (http://news.ycombinator.com/item?id=1880981) pointed out, this is part of the ANSI standard for SQL, and not exactly due to MySQL's handling of NULLs strangely (there, also fixed the apostrophes for you).
You need to read up on the ANSI standards for sarcasm.