A couple were returning home after a night out. The husband forgot his keys so the wife, a little annoyed, uses her keys to try to open the door. But the lock wouldn't budge. She asked her husband to turn on the flashlight and tried it again. The lock wouldn't budge. After trying for 20 minutes, she finally hands over the keys to the husband and says, "Here, you try".
The husband inserts the key into the hole and turns. The lock opens immediately. No sooner the husband takes the key out of the locks, the wife quips, "You see... now THAT'S how you hold the light!"