Maybe I just don't understand enough about pop culture to get this reference in The Jerk. Basically, Navin (Steve Martin's character), who seemed to have trouble feeling the rhythm of music his family played, was very impressed with this music he heard on the radio. He started tapping to the beat and snapping his fingers and said the following:
"It's unbelievable! I've never heard music like this before! It speaks to me!"
And then his mother was about to say something to him but his father stopped her:
"Let him go...".
This is meant to be a joke, but I don't understand it. Anyone care to explain?
Here's that scene on YouTube.