Yes, so too if they all farted at the same time the gasses would have a “gastronomic” effect on the weather patterns and maybe the Sun would come out and we’d all get a tan. We could line all humankind up at one “edge” of the world (the world is flat don’t forget), right near the waterfalls face them inland towards the Sun, fart, and we’d be propelled about 2500 bahillion miles heading for a very hot ball of gas. If we did it the other way around we might just blow ourselves up, so, so take that into consideration when planning this event please.
That apart, no, you are relying on each person carring a stone and I don’t, not that I know of. If they all lost one stone each, or indeed carried one, then we’d have random piles of stones everywhere. Nd what constitutes a stone, is it just a fat pebble?