I work in the local secondary school and the internet is provided by an external company, they have different security policies and the default one which students use is locked down.
but only locked down due to monitoring and statistics, if a student picks up a new proxy which isnt blocked all of a sudden my school's 'most surfed to website' becomes said proxy, then this really starts to multiply as their mates start to use it.

I was told they can predict and watch the trend as the proxy makes its way around the different schools in the town and surrounding areas.

Kinda glad I dont have to block stuff manually, it would be a fully time job in itself. Ofcourse I have the most relaxed policy on my machine so I dont care about anyone else LOL