I think repercussions or punishment have less and less motivation in older people who have developed a correct (socially acceptable) sense of what is right and wrong. The repercussion part is a useful teaching tool that can be applied to anyone while they develop the desired thought patterns - unfortunately society is full of people sitting in jail who can't seem to get it right
As for what I do...
I don't think I'd do anything directly to a specific person like murder, rape, stealing, vandalism, etc. I would certainly stop paying my bills and going to work. Probably stock up on a lot of food and spend the last few days with my family.
I have to wonder though if the world would end simply because someone said it was? Sort of a self fulfilling prophesy.