What's an IH mirror?
A mirror is an alternative location on the web where an identical copy of a particular site is hosted so that you can still get to it if the main site is bogged down or out of service. Some domain names have been outright hijacked and others are just interesting site names that are redirected to ItsHappening. The site is too offensive for some, but there are a lot of interesting characters there if you don't mind digging through the crud.
Here is an article about IH that is a good read.
http://www.bostonphoenix.com/boston/news_features/top/features/documents/02460739.htm