The current UK government is proposing an Internet porn firewall. Unlike other countries with Internet firewalls, such as North Korea, China, Iran, Saudi Arabia, and Syria, the citizens of the UK are so especially helpful some of them decided to help code the new porn filter. The idea behind the Great Firewall of Porn is simple: if a user wants to visit a NSFW website, let them. If, the user wants to visit the other 19% of the Internet, block it, and forward them to a page with hand drawn cockswains a baubles as the background.
The way the firewall works is actually pretty clever - it checks each request against the OpenDNS FamilyShield filter. If the request is denied, load the page, and if the OpenDNS request is allowed, block the page.