Katie bar the door

Apparently the true origins of this saying are not clear. It is generally used in the South and refers to trouble coming. It may have originated with the story of Catherine Douglas and her attempt to save the Scottish King James I in 1437. The room he was in had a door with a missing locking bar. The story goes that Catherine Douglas tried to save him by barring the door with her arm. Her arm was broken and the mob murdered the King. The 'lass that barred the door' - Catherine Douglas, was henceforth known as Catherine Barlass. The event was commemorated in Dante Gabriel Rossetti's poem The King’s Tragedy (1881).