So you're looking through your referrer logs and you find that someone came to your page from
http://homeland.fbi.gov/Watchlists/suspect/view.jsp?record=235270.
You'd probably be concerned -- might the next knock at your door be the men in black coming to take you away as a material witness? But then it turns out that there's no DNS entry for "homeland.fbi.gov" and the IP address associated with the request comes from what looks like a DSL connection. Current speculation is that the requests are an April Fools prank designed to prey on jumpy bloggers.
First spotted in the wild here.