Public: Playground
Financial District Ball Pit   (+1)  [vote for, against]
Surprise a suit

Ball pits are surreptitiously built underground in areas where busy and important people go. Ventilation grates and manholes are modified to be trap doors. Put ladders somewhere so they can crawl out.
-- the porpoise, Apr 27 2015

NYSE stock exchange floor would be a natural fit.
-- RayfordSteele, Apr 27 2015

Be sure you do not label the balls.

( Tourists and others would steal them for souvenirs. And soon people would be dropping into an empty pit and crawling out looking for someone to sue. )
-- popbottle, Apr 28 2015

random, halfbakery