There's a strange urban legend that seems to have popped up as of late, that white rocks in a house's front yard means the inhabitants of that house are swingers. The swinging community at large isn't sure where this rumor came from, but many say they've heard this themselves, and some have placed white rocks in their front yards to reaffirm their “secret code swinger status.”
In our research and discussion with many swingers (and a very unscientific survey of those swingers) we've found that only one in the group put white rocks in front of their house to indicate they were swingers.
Those who assert that this at least once was true also perpetuate the legend that swinging started on army bases, where men who were on the base “took care” of the wives of men who were not. (Presumably with their knowledge and support, or this is a very mean story.) The rumor then suggests that the houses of those who were in on this scheme had white rocks in front of them.
So, while it's POSSIBLE that the above paragraph is actually true, there's a lot of debate about it, and since no one really likes to talk all that much about their proclivities, let alone advertise them to the neighborhood with an identifiable symbol, we probably will never be able to tell the difference between those swingers with white rocks, and the regular people who just like white rocks, and those who use white rocks to edge their driveway, and those who use white rocks to define the edge of their property.