The English and the French have always been fighting each other. Back in the time of crossbows, they figured out that, rather than take prisoners, it was easier to just cut off the first two fingers. Then the "prisoner" couldn't shoot his crossbow. This is the origin of the sign in Meyers' picture: "I can still kill you."
The crossbows are gone, but the sign has lived on and spread way beyond England and France. The original sentiment is pretty much still shared between the English & French. This is also how the Brazilians took it when Nixon walked out of Air Force One on the runway in Rio de Janeiro flashing two "Victory" signs.