The following passage, taken from "Zap! The Rise and Fall of Atari," is an account of Pong's first night in the bar:
One of the regulars approached the Pong game inquisitively and studied the ball bouncing silently around the screen as if in a vacuum. A friend joined him. The instructions said: 'Avoid missing ball for high score.' One of [them] inserted a quarter. There was a beep. The game had begun. They watched dumbfoundedly as the ball appeared alternately on one side of the screen and then disappeared on the other. Each time it did the score changed. The score was tied at 3-3 when one player tried the knob controlling the paddle at his end of the screen. The score was 5-4, his favor, when his paddle made contact with the ball. There was a beautifully resonant "pong" sound, and the ball bounced back to the other side of the screen. 6-4. At 8-4 the second player figured out how to use his paddle. They had their first brief volley just before the score was 11-5 and the game was over.
Seven quarters later they were having extended volleys, and the constant pong noise was attracting the curiosity of others at the bar. Before closing, everybody in the bar had played the game. The next day people were lined up outside Andy Capp's at 10 A.M. to play Pong.
~~quoted from classicgaming.com:
http://www.classicgaming.com/museum/pong/index.shtml