3. Pain
In English: "bread." Whether it's a baguette — and there are many different kinds of baguettes — or any other types of bread, to not indulge in bread while in Paris is wrong. They are, after all, the bread capital of the world. Although why this is, is still debatable. I've read it has something to do with the exact altitude of the country. I've also read that it's not that complicated; it's simply that the French just know how to make bread far better than anyone else in the world.