I always answer the doorbell.
I admit that there have been times that I wanted to pretend I'm not home, but I answer the door anyway. And there have been times that I regretted it. Ha!
Santa Claus. 乂^◡^乂
I believe it was a UPS delivery person.
Mormon missionaries. It's hard to tell them no or be rude to them because they're so relentlessly pleasant and polite.
That's a funny one at my house. When the Jehovah's Witnesses come to our door, my wife pretends to be not home, but I go and answer the door. Since I am an atheist, I get a kick out of having an intellectual discussion about how I know that there is no such thing as God while they keep trying to push their literature at me!