Promises are as thin and fragile as pie crust, and people make them so often but are rarely inclined to keep them. "Pie crust" is often written as a single word. A: "He promised to help me study for my exam, but he didn't show up!" B: "Well, promises are like pie crusts, Sarah—easily made, easily broken." A: "I promise that I will never do something like that again." B: "Not good enough, Tom. Promises are like piecrust—easily broken."