I want to use my pi as a proxy so I can access sites in school that C2K block. It is getting so ridiculous that you can't even get on yahoo forums because it is a "Message board and forums" and all the teachers are getting annoyed that Youtube is blocked as well

Is there a way I can connect from my C2K account to my home network, port forward to my pi, and use my pi as a proxy?
I tried all the proxy sites but they have been blocked - along with Google half the time!
Any help would be greatly appreciated.
Thanks,
Ethan
P.S any help at all is appreciated