Wiktionary
butcher's apron
n. (context UK Ireland derogatory English) the http://en.wikipedia.org/wiki/Union%20Jack.
Usage examples of "butcher's apron".
Then, when I had taken off my butcher's apron and washed, I went back to the Pillar Room.
One Friday afternoon I hand over my gauzy cream tunic and slip into a kind of butcher's apron, epically and namelessly stained.
She landed on a man in a butcher's apron, knocking him to the ground.