Spinal Tap Trivia :-)

I heard this on a Unwigged and Unplugged Concert by Spinal Tap that I watched today.   During the middle of the concert, Spinal Tap has a question and answer session.  An interesting question and answer was the following:

• QUESTION:  How much was scripted and how much was pure improv during the shooting of Spinal Tap?
• ANSWER:   EVERYTHING was improv except for two lines:
1. "I say, Tap into America."
2. "Straight from Hell, Spinal Tap."

It is an amazing to think that the number one cult film of all time was shot by turning on the camera and just make up the lines as it was shot.