@Ticomaya,
What DrewDad said.
The implied punch line in hingehead's joke lies in the double meaning of "server" (as barman on the one hand and as the other side of a TCP transaction on the other hand.) It took me a while to get it because the word "server" isn't even spoken.
On almost all computers, 127.0.0.1 is the IP address of "localhost", meaning your own "home" computer. So DrewDad's joke is a pun on the Wizard of Oz. (IP addresses consist of four numbers, each between 0 and 127. They are to computer networks what phone numbers are to telephone networks.)