What is the "V" sign?

The "V" sign (consisting of sticking up the two first fingers on the hand, with the palm facing towards you) is used throughout Britain as an insult.

Origins

These are a little hazy and steeped in myth.

The most well-known origin dates back to the Battle of Agincourt between the armies of the English and French kings. The English bowmen were an important part of their kings army and the French king decided that any captured english soldier was to have his first two fingers cut off, to prevent him from being able to use a longbow. As an act of defiance against the french generally, the english came to stick their two (attached) bow-fingers at them - a way of saying "we can still fire our longbows at you" (or more generally, just be mean "go stuff yourself!" or stronger). Over the years, this simply became a general way of insulting people in the British Isles.