It's polite to hold the door open for people.
It's raining heavily as Paul pulls up to a convenience store, and as he gets out of his car and runs for the door he sees someone else running up.
Paul wants to get inside.
Paul opens the door and holds it open behind him for the stranger.
Paul quickly opens the door to get out of the elements and steps inside.
The stranger thanks Paul for being so considerate and flashes him a smile.
The stranger is annoyed at Paul for not holding the door open for them and calls him a jerk.