A rhetorical question is a way of asking a question that doesn't necessarily need an answer. It's like when your mom asks "Do I look like I was born yesterday?" when she already knows the answer. People use rhetorical questions to make a point or to get people to think about something. They can make a statement or suggest an idea without coming right out and saying it. So, it's kind of like asking a question that you already know the answer to, but you're not really looking for an answer - you just want to make a point or get people thinking.