While standing in the run-up area waiting to taxi onto the runway, the pilot of the Cessna heard a loud noise and felt movement of his airplane. He shut the engine down and got out to see that the left wing of a tail-wheel equipped Piper had collided with the left side of the Cessna’s rudder and vertical stabilizer. The pilot of the Piper reported that he was taxiing to get fuel, with no intent for flight, and as he turned off the taxiway to the run up pad in order to run the engine prior to getting fuel, he saw the tail of the Cessna directly in front of him. He applied right brake action and swiveled his aircraft to avoid a direct collision with his propeller. The pilot added that he had no idea of why he wasn’t able to see the Cessna in time to avoid the collision.