Nebraska and Iowa strictly forbids the PA announcers to do any play-by-play while the ball is live. If we hear the PA announcer doing play-by-play, it's an USC on the home team.

Edit: I missed another one about the band. Same rule applies to the bands. They cannot be playing during live ball, or USC against offending team (usually home team because not very many visiting teams can afford to drag their band along!).