murder board

Of US military origin. Murder refers to a group of crows. Petty Officers in the US Navy have a bird on their rank insignia commonly referred to as a "crow", and the petty officers themselves are sometimes referred to as crows. A murder board refers to when a junior sailor would go through a rigorous questioning session by a group of more experienced petty officers (crows, or a murder) in order to prepare them for a further oral examination conducted by higher ranked military personnel in order to attain professional qualification or some other purpose.