TL;DR: To get the Disciplined Badge, you need to delete an answer which is not accepted with 3 or higher score, then undelete it a minute later. You will not lose any reputation this way and earn a free bronze badge, since it is legal and known, I advise everybody to do this.

Edit: I changed my mind. This was a bad idea. At least I learned something.

Disciplined Badge : Deleted own post with score of 3 or higher. http://stackoverflow.com/help/badges/37/disciplined

I don't see how this badge affects the community in a positive way, it might be doing more harm to the community than good.

Even if this badge is moderated for abuse, it wastes the time of moderators for a useless reason: "Some guy deleted a good answer for this stupid bronze badge"

( Negative effects of this badge / Positive effects of this badge )
Is definitely over 1 and I think it should be deleted or stop from being earned anymore.