barbers pole

from The Collaborative International Dictionary of English v.0.48

barber pole \barber pole\, barbers pole \barbers pole\n.
   a pole with red and white spiral stripes; -- usually found
   outside a barbershop.

   Note: It is often electrically powered, so as to be turning
         when the barbershop is open for business and stationary
         when the shop is closed. It symbolizes the practise of
         surgery, some aspects of which which used to be
         performed by barbers.
         [PJC]