Read this strip at gocomics.com
The previous Sunday strip had mostly the same idea, but with a different payoff.
I think this could be taken to show how careful Schulz is to mine his premises well. As I've said before, drawing a daily comic strip is one of the most creatively demanding occupations one could hope to find. Imagine the pressure of having to come up with one joke a day for the rest of your life. Schulz is showing good sense by getting additional gags out of his premises.
