Sorry to bring up an old thread: but this is an old trick we used to use at College, Open up a SSH connection to your home machine using port 443, because most firewalls allow it for HTTPS and you can use the tunnel for the internet, that is why there seems to be 'no pattern'
of course, once the other students work out that you can do it, you end up being the local jailed shell host
*edit, also SSH won't be so easily sniffed at,*