Need: 4 (or more) scouts.
The first boy is squatting as though sitting on an invisible bench. The second boy comes in and asks what the first is doing.
"I'm sitting on the invisible bench."
"Can I join you?"
"Sure, there's plenty of room."
The second boy pretends to sit.
A third boy comes along, and the scene repeats.
Go on for as many boys as you want.
When the last boy comes along, asks, and is answered, he says "But I moved it over there this morning!"
AAAAHHHHHH!!!! All seated boys fall down.