B warning mark
Something bestowed upon unlucky pupils who forgot to bring a required book to a language lesson. The accumulation of three B warning marks (or any kind of warning mark, for that matter) got you a language faculty detention. This rarely happened due to the embarassment experienced by everyone yelling "Beeeeeeeeee warning maaaaaaaaarrrk!" at you every time you forgot to bring in your French exercise book.
written by Le*po*d *loom, disapproved by Phil