Sockpuppetry
Sockpuppetry is the act of pretending be several different individuals within one community. It is usually an internet phenomenon, but here is the equivalent real world example: you go to a picnic with four other people, but you have your hand up three of their arses, and the one left over cannot tell.
Aside from being impossible, a bit inappropriate and not much fun for the sockpuppets, sockpuppetry is usually a scurrilous activity. It is often used by greks to create an instant support base for whatever pointless e-scheme they have recently concocted. Sockpuppetry can be used to perpetrate some forms of electoral fraud.
Sockpuppetry is like having the ability to dual, triple or quadruple-boot a computer into different operating systems. Some cultures consider this a form of half, third or quarter-stepping; in some places this carries the death penalty.
Like mathematics, sockpuppetry is a slippery customer for the authorities and has evaded capture for many centuries. Sockpuppets revel in any attempt to uncover their true identity, so the best way to deal with a suspected sockpuppet is to ignore them. Eventually they will not be able to help but to let slip some critical information, in an attempt to arouse just a little suspicion, a clumsy, frustrated spurt of knowledge which will undoubtably 'give the game away'.
Sockpuppetry has a strong association with some other uses of socks.