The barracks is a building where unmarried military personnel live, it is mosty inhabited by men. A barracks bunny is a female military personnel who lives in the barracks and has random casual sex with many men in the barracks.
CPL Jones: " man, i havent gotten a piece in a good minute...ima hit up "so and so" the barrack bunny, shes a sure thing"
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi