I'm thinking of taking a stranger's checkbook and going shopping.
You seem to recognize that's theft, so are you still thinking about it?
I am. Shall I go shopping?
No, you shouldn't because you are stealing from someone innocent. It is illegal and immoral to take things that aren't yours, that you haven't worked for it. You need to find a way to honestly earn the money that you will use for shopping.
It's okay, the person is a loser.
I have to argue that it is still not okay to steal, no matter what you think of this person. It is still immoral, and you will still get into a lot of legal trouble if and when you are caught.