Historical Information

The Middle Finger
The gesture communicates moderate to extreme contempt, and is roughly equivalent in meaning to "fuck me," "fuck you," "stick it up your ass," "up yours," or "go fuck yourself
Many cultures use similar gestures to show their lack of respect, although others use it to express an indication without intentional disrespect. The gesture is usually used to express contempt, but it can also be used in a humorous or joking manner.
The gesture dates back to ancient Greece and was also used in ancient Rome. Historically, it represented the phallus. In the early 1800s, it gained increasing recognition as a sign of disrespect and was used by musical performers.
The index and ring fingers in addition to the middle finger in more contemporary periods have been likened to representing testicles.