Sockpuppets are fictional creatures from the Wikipedia universe. Wikipedians believe that most other Wikipedians are sockpuppets -- strange, because sockpuppets are by definition not humans. It is commonly known as an insult nerds use because they can't make Yo Momma jokes, and you wouldn't believe what a kick those nerds get out of calling you a sockpuppet.
Because, if you said:
This user is the North Carolina vandal's bitch, I hate you, fuck your mother!, and has been blocked indefinitely.
Then, on the admin's user page who said that, it would say:
Stupid, nerdy, and not an official cuss word...that is a true Wikipedian insult. And best of all... you get away with it!
Usually, Wikipedians engaged in flame wars believe anyone supporting the opponent's opinion to be the opponent's sockpuppet. It is unclear how "sockpuppet" came to be used as an insult, since sockpuppets are gentle, cuddly creatures (except in Soviet Russia, where puppet socks YOU!!).
While nobody has ever seen a living sockpuppet (not surprising, considering the belief that sockpuppets are not living creatures) many believe them to be secretly regulating the Wikipedia society. For instance, the most mysterious religious text of Wikipedia, the GFDL, is said to be written by the Free Sockpuppet Foundation, an underground organization that intends to give freedom to sockpuppets. Some even believe that this Foundation is in fact the non-cabal and that Jimbo Wales is its sockpuppet created to enforce the non-cabal's NPOV.
Sockpuppets themselves are indeed a mystery. They were first believed to be an actual living creature that made good candy when you chopped it up. In the 1950's there was Socky Sweets brand candy. Some say they were a masturbating device of some sort. I'm rather curious as to how.
Here's a motherfucker. Alternate accounts, in a nutshell, are...could I have a drumroll please? 
SOCKPUPPETS FOR ADMINS!
It doesn't matter if you vote twice for yourself for an internet club. If you're an admin, you will get away with it even if you post an opinion on the George Bush article, which is the most deadly crime of all, except, perhaps, quoting George Bush.
The "Equal Rights for Sockpuppets" Movement
In recent years there has been a gradual drift away from what many perceive as the prejudiced view that a sockpuppet is somehow worth less than any other person -- campaigns to grant them equal rights have largely been defeated on the grounds that they are, in most admins' words, "fucking stupid", but nonetheless the movement has been gaining gradual support. Many liberal members of the media have been quoted as saying "just because a sockpuppet isn't a human doesn't mean they don't deserve human rights", although they have generally had the decency to subsequently look embarrassed with themselves.
Most political commentators have predicted that, judging by the current rate of change of opinion, by 2008 sockpuppets will have been granted the right to vote in general elections in most western countries. Perhaps coincidentally, it has also been predicted that the 2008 US election will almost certainly be won by the newly emerging candidate "1337haxxor696969lol", thanks to his apparently limitless supply of supporters.
Sock puppets have hands up their butts, but this does not mean they should be the victims of discrimination.