Red, blue, white: There is a frightening story behind the colored stripes at the hairdresser. The barber's post is a sign of bloodletting - blood and bandages cover the post.
The red represents the blood, the white represents the bandages that stop the bleeding. The blue symbolizes the veins. These had to be cut open to let the blood out. The other theory interprets the blue of the post as a reference to the American flag. As the barber pole rotates, it feels like the stripes are up or down.