Mashable reports that on the 4th of July, Wikipedia — "the free encyclopedia that anyone can edit" — went down for a number of hours.
There's been a lot of speculation about how this happened, but I think I've stumbled up on the answer.
Someone edited the entry for "Wikipedia" on Wikipedia to read like this:
Unable to process the definition of itself, the site immediately crashed.
A similar incident happened in 2005 when a prankster changed the site's entry to read "Wikipedia is my balls," and the entire site became replaced with an image of my balls.
That time it wasn't reported that the site had "gone down." Instead, it had "been sacked."