None. Sit on the floor.
Curl into a tight ball, arms wrapped around knees. "I am a house. The door is closed." Open arms slightly. "The door is open."
Most kids immediately copy. Then start narrating who lives in the house. Then they want you to be a house that they go into.
"I am a tiny house" (curl tighter). "I am a tall house" (arms up). "Who's knocking?" Add doorbell sounds.