You could also run your own browser off a USB pen through a host of proxy servers, like Firefox with the FoxyProxy plugin, if your school has banned the proxy websites, too. It sounds like they're using a list of banned words, so it's just a matter of finding a proxy whose title doesn't contain any of those words. You could try proxify.co.uk camolist.com goodhider.com fastnopopups.com etc. etc.