It's call: how close can I get to the TV before Mom & Dad screams?
Answer:
Mom - 10 feet, or eyes pinned to TV direction
Dad - depends, with 'weapons' in hand, 3 feet. without, 18 inches. Then of course if Dad himself is about that close and was paying attention to the TV.. He can get his hands up to 3 inches to the TV before dad notices.
Very fun game!