Hmm... we used to have that on our computers when I was in highschool. We would find these sites that would imitate an old-school web browser in your current browser. And then it would bypass the blocker.
I don't remember the name of the site we used or anything though.
we have that too, the school blocked most of the proxy sites but we keep finding new ones...right now we use www.pixelproxy.org and its been working well