1. When people can readily have something, they don’t want it. But when you tell them they can’t have it, that’s all they want. There’s nothing like the attraction of forbidden fruit
2. Jody’s parents told her not to date Dennis because they think he might be a bad influence on her. But now that they’ve made him forbidden fruit, he’s the only boy who interests her.

The expression originates from the Biblical story of Adam and Eve, where God forbade Adam and Eve to eat the fruit from one of the trees in the Garden of Eden. This made the fruit so tempting that they were unable to resist eating it.