Geeks Are Sexy Blog has a neat round-up of some of the geekiest T-shirts on the Net. They're mostly oldies but goodies, and I think you can get them over at ThinkGeek or maybe do a search on Teenormous (I wish they were linked to the sellers): Link - Thanks Yan!
The bad thing is, thinkgeeks ideas are far from the super-geeky anymore. Most of their jokes and one-liners are very mainstream now.
"Network 127.0.0.0 is reserved for IP traffic local to your host. Usually, address 127.0.0.1 will be assigned to a special interface on your host, the loopback interface, which acts like a closed circuit. Any IP packet handed to this interface from TCP or UDP will be returned to them as if it had just arrived from some network. This allows you to develop and test networking software without ever using a “real” network. "
http://www.faqs.org/docs/linux_network/x-087-2-issues.ip-addresses.html