I saw http://news.ycombinator.com/x http://news.ycombinator.com/x in my referer logs, what is this for? When I clicked on it, it said: Unknown or expired link,

I saw http://news.ycombinator.com/x http://news.ycombinator.com/x in my referer logs, what is this for? When I clicked on it, it said: Unknown or expired link, like if you leave the add comment window open too long.