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Boris Johnson prefers to swear at people with two fingers rather than just one.
Last week a cyclist was photographed raising his middle finger at the mayor as the pair passed each other on London's new cycle super highway.
Twitter user @mrchrisjohn asked Boris today: "Will you be asking for this hand signal be added to the Highway Code?" with a picture attached of a cyclist swearing at the mayor.
The mayor replied: "I believe in tradition and we insist on the two finger salute in London."