Why Do We Say That?

NAIL YOUR COLOURS TO THE MAST
In battle a ship surrendered by lowering it's flag. If you nailed your colours to the mast you had no intention of surrendering.

PANDEMONIUM
This comes from John Milton's poem Paradise Lost. In Hell the chief city id Pandemonium. In Greek Pandemonium means 'all the devils'.

EARMARKED
This comes from the days when livestock had their ears marked so their owner could be easily identified.

SCAPEGOAT
In the Old Testament (Leviticus 16:7-10) two goats were selected. One was sacrificed. The other was spared but the High Priest laid his hands on it and confessed the sins of his people. The goat was driven into the wilderness. He was a symbolic 'scapegoat' for the peoples sins.