So I'm going to be charitable here and presume that whoever compiled that internet monitoring watchlist at the Department of Homeland Security thought that "Miss Thirteen," at www.msthirteen.com, was a site about the ultraviolent Mara Salvatrucha or MS-13 gang, which originated in El Salvador and now operates in a number of US cities.
Quote, mangle-translated from the original German by Google: "Change in our lives, accompanying us from our childhood into adult life. The hormones go crazy and actually everything is always much too confusing."
Perhaps this was the source for the bad link. And perhaps the fact that this site was included in the watchlist tells us something about how the watchlist was compiled, or how reliable its contents are as a disclosure of what the agency's monitoring.
(thanks, Elizabeth Gettelman!)
Update: Probably a more simple explanation — the content of the site changed over time. The version of the document at Cryptome was published in 2011. The Reuters article that made the rounds today appears to be based on a new version of the document for 2012, which we haven't seen. BB reader Todd Towles says, "According to DNS Stuff, the current msthirteen.com domain was created in Sep 2011. According to the WayBackMachine, the site was about MS-13 on Feb 2010.