It's not okay to steal something from someone.
Amy needs a graphing calculator for an upcoming test and knows that her brother Mark has one.
Amy wants to use Mark's graphing calculator for her test.
Amy asks Mark if she can borrow his graphing calculator.
While Mark is downstairs with friends, Amy goes into his room and takes his graphing calculator.
Mark happily lends Amy his calculator, and she passes her test.
Mark notices that his calculator is missing and argues with his friends over who took it.