Go to the scene in the movie where Billy is sitting in the bathtub with his bottles of shampoo

and conditioner. After he goes through the shampoo is better and conditioner is better joke, you can see him catch the swan faucet out of the corner of his eye. If you look close, you can see him think twice and then add-libb the line, "Stop looking at me swan!" If your television volume is turned up you can hear the the director and cameramen and whoever else burst out laughing in the background right after he says it.