I guess I've just watched too many Twilight Zone episodes. I remember how in one episode a guy had built a bomb shelter, the only one in the neighborhood, and when it looked like the bubble went up, suddenly all his neighbors felt he "owed" it to each of them to let them come stay in his shelter with him. I think in the end they ended up busting it or something, then found out the bubble hadn't gone up, and they were all just jerks.