I did exactly that as an intern. The boss blocked traffic for everything except tcp 80 and 443 in an attempt to block IM. I set up a tunnel to my house on one of those ports and arp cache poisoned my coworkers so I was their default gw. Only the boss still had filtered Internet and didn't understand how.

Hehe, that's funny. There are not that many opportunities to use your knowledge about the plumbing of the internet to good effect but that definitely was one of them.