My parents live near a stone quarry.
As an early teen my friend and I would wait until the quarry closed and would then scramble up the newly blasted rockface to investigate the new landscape - From time to time we'd find a precariously balanced rock that was just begging to be shoved off the cliff so we could gleefully watch it tumble onto the surface below.

One time there was a particularly large one (perhaps the size of an oldschool Mini) that was begging to be shoved. After some shoving it was clear it wasn't going to move so we resorted to lying on a handy flat rock just behind it and using our legs we were able to get it rocking back and forth.

Backs straining we finally got the thing to topple and leaned forward to watch its descent... the avalanche it created was one of the best we'd seen.. up until the point that we realised that most of the cliff face beneath our feet was starting to shift downwards.

We ended up scrambling up a rapidly accelerating avalance of huge rocks expecting to be smashed to bits on the rocks below but somehow managed to scramble high enough onto a more solid part of the rock face.

After a nervous laugh we sat back to watch the dust settle, fearless as kids are.
( Airman Gabber Living life like a 70's BBC presenter, Fri 5 Jul 2013, 14:50, Reply)