It's difficult for hearing students to get used to using NMS. This is a fun way to use NMS in a game format to ease the pressure of "making faces".
Distribute cards to students. Have them go to the door, open it as if what is on their card is on the other side of the door. Make sure that they aren't being TOO silly. Have the other students guess what is on the student's card.
Shy students may need help or suggestions.