Eggs and Shank Bones

This story may have taken place in 2008, the last time erev Pesach fell out on Shabbos. It takes place between a wise son and his father on the Seder night.
Chochom: Tatty, some of the items on the seder plate are incongruous.
Tatty: This is the same setup of the seder plate I use every year.
Chochom: I know, but this year it doesn’t seem right.
Tatty: Why is this year different from any other year?
Chochom: This year erev Pesach fell out on Shabbos.
Tatty: I know, I read a pre-publication edition of The Jewish Home that will, be”H, be published in 13 years. We are supposed to reverse two words in the Hagaddah at the end of Maggid; zevachim and pesachim. But what does that have to do with the Seder plate?
Chochom: The reason many reverse the words is because there is no Chagigah brought on erev Pesach when it falls on Shabbos like this year.
Tatty: Ah, now I know why that is related to the Seder plate.