"If you confess what your little dirty little sins are, you're going to get a whole audience laughing..."

"... because they all have the same dirty little sin." Said by Shelley Berman, explaining the secret comedy.

From the same little article, Fred Willard:

The perfect comic is the comic who will say something and you say: "Oh my God, I thought I was the only one who felt that way. I was, had this secret all my life. I thought I was a pervert, or I thought I was a racist, or I thought I was an idiot."

(That also sounds like the secret of the Internet.)