When I was at college my mate used to keep all his used coke cans, and stack them in a huge triangle against the wall in his bedroom.
We used to amuse ourselves seeing how many we could remove before the whole lot came down - with an almighty clanging roar.
One night we had removed loads and it had not fallen so we left it standing.
Apparently at about 4.30 am, when he was in a deep sleep it collapsed.
He thought the world was ending. I still laugh about it years later.