I did an impromptu street performance with Kaufman one night (I was drunk, he was with his woman), and it is one of my proudest moments ever that I made him stop and laugh at something I did. If you think he was (is?) funny on stage, he was (is?) faster and funnier off. He was (is?) one of the few people on the planet who could make me laugh in person.
I hope this is true, but somehow, I seriously doubt he was able to bottle that energy for 30 years as a stay-at-home father. I suspect this may all have been a planned tribute to his genius.