As usual, in the midst of some daytime “serial”-the Sunday strip would be independent of it(being totally unrelated, having nothing at all to do with the current daily serial, or the daily strips at all.)
Neither had I, until after I was grown up. I had the Peanuts book “There’s A Vulture Outside” which contained all Sunday strips, from this general era(including this), and I too was baffled at CB’s use of the word “rhubarb” in last panel.
As usual, in the midst of some daytime “serial”-the Sunday strip would be independent of it(being totally unrelated, having nothing at all to do with the current daily serial, or the daily strips at all.)