I open the door for people if I arrive at it first. I expect the same to be done for me. If a guy refuses to enter a door I open for him, I do consider that annoying. I understand the idea of chivalry, but don't waste my time. Other than trying to do nice things for people, the reason why I open my own door.. is because I am going somewhere. I don't have the time to waste playing "No, you go first."