I think Christopher Guest plays one of the sperm trying to calm down Woody just before they ejaculate? It is not listed in the credits,nor on Guest's IMDB credits, but I think it was him.
What is it, Old Nehamkin? You are not looking well.
It looks a bit like him, but it is actually Robert Walden. There is are some more recent pics of him here:
http://www.vineyardplayhouse.org/articles/2003/article0315.html
http://www.availablelightphoto.com/portraits_walden.html
http://mywebpages.comcast.net/matchgame/3X5Picturesw-z.html
However, I am convinced that the woman who gets her leg sucked on in the restaurant in the italian episode is Princess Livingstone, who was the old hag in the movie "Mudhoney."
Thanks. I can see the resemblence between Chris and Robert.
You see, what I think he was thinking was, "Goddam Rodin. Three drinks and I'm nude."