If you check your traffic sources (as I often do) you may notice the following URLs/Sites come up in your lists:
PLEASE do not click on any of these links. It's a new method of advertising called "referer spam". Here is a good explanation from Matt Cutts at WebProNews.com:
“A referer is just a simple HTTP header that is passed along when a browser goes from one page to another page, and it normally is used to indicate where the user’s coming from. Now, people can use that, and change the referer to be anything that they want. They can make it empty, or there are some people who will set the referer to a page they want to promote, and then they will just visit tons of pages around the web. All the people that look at the referers see that, and say, ‘Oh, maybe I should go and check that out.’ And the link – whenever there’s a referer – it doesn’t mean that there was necessarily a link, because you can make that referer anything you want, so there are some people who try to drive traffic by visiting a ton of websites, even with an automated script, and setting the referer to be the URL that they want to promote."
There is nothing you can do (unless you are a computer whiz) to get rid of it, so please just ignore it and don't follow the links. :)