I remember seeing piles of them swept up around coke machines. Well that and piles of dead crickets. But at least the cricket biodegraded eventually. The coke machines had a slot to place the pull tops in after you opened the can of cola, but very few people actually used it. Most apparently just dropped them on the ground. The same was true for the pop tops on cola glass bottles. Those were much more wicked to step on. Both were littering the ground in those days.