I'm going to answer the door for the pizza guy in my boxers
Why would you answer the door for the pizza guy in your boxers?
Maybe he'll like it
Well, it's expected that you are fully dressed before answering the door. You never know who will end up showing up. It might not even be a guy and you will end up being in a compromising and embarrassing position.
I'm not that kind of guy.
Even if you don't think you'd be embarrassed, you should think about how the delivery person would feel. It might make them really uncomfortable, and you don't benefit in any way.