Long story short:
The Bill Callahan era had many folks questioning what was wrong with the Husker's defense. Quite a few people thought that a b******* would inspire the defense to turn things around. Those of us with more level heads knew that the fans' shirt color was not the problem with the defense. However, the call for a b******* continued, triggering one by the student section (can't remember when), which was later labeled a "failout". In the end, the higher-ups here on HB took their neurologists recommendation of banning the word, to avoid further damage.