1 and 2. The Yooks and the Zooks argued over how to butter bread, while the U.S.A. and the U.S.S.R. argued over how a government should be run.
3 and 4. The difference between the two cultures is that while the Yooks eat their bread with the butter-side up, the Zooks eat their bread with the butter-side down. The conflict between the two sides leads to an escalating arms race, which results in the threat of mutual assured destruction.
5.The border patrol employed at first to keep the Zooks under control represents the Truman Doctrine and the Marshall Plan. The Snick-Berry Switch that Grandpa Yook uses is meant to be military aid. Zooks eat bread "butter side down," which represents communism.
6.Eventually, each side possesses a small but extremely destructive red bomb called the "Bitsy Big-Boy Boomeroo", and neither has any defense against it, so while the Yooks' patrolman and VanItch drop theirs, the Yooks and Zooks will have to stay underground to make sure that they don't get blown away.
7.The wall symbolizes separation. When the two sides enter the arms race until they eventually develop the Bitsy Big-Boy Bomeroo. The weapon is so dangerous that the two sides enter a stalemate, simlilar to the Cold War and the nukes produced by the U.S and the Soviet Union.
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