Start a Round of "Would You Rather?"
It's simple but shockingly effective at beating boredom, especially in car backseats. Ask your kids "Would your rather...?" questions, such as, Would you rather have Green Lantern's superpowers or Superman's? Would you rather have breakfast for dinner or dinner for breakfast? Would you rather be a dog or a cat or a hedgehog? The whys of their choices, of course, are the most riveting. Don't forget to make the last one something you can actually do for them—for example, Would rather pull over at the next rest stop to go to the bathroom or eat ice cream?—even if you know the answer.