Baffling Bowling Pins

The magician has a spectator assist in a 'you do as I do' routine. He freely displays two bowling pins and two tubes. He gives one set to the spectator. He instructs the spectator to exactly duplicate his movements. However, every time the spectator lifts his tube, his pin is upside down! The magician offers to switch pins and tubes, yet this doesn't help.... Complete with two seven inch plastic pins, two cardboard tubes, instructions, and secret gimmick.