A young couple are about to go on a holiday. The guy is waiting for his blonde girlfriend at the airport, when she arrives carrying a door.
BF: "What are you carrying?!"
GF: "You know how burglars break down the front door to get into houses?"
GF: "Well, if I take my front door with me, then burglars can't break the door down, which means they can't get in and take anything."
BF: "Ok then. What are you going to do if you lose the door, or if the door breaks?"
GF: "I thought of that. I left one of the side windows open so I can get in through there."