Of course, by today’s standards it’s pretty mild. Nevertheless, if you told Great Aunt Sadie to ‘shut her trap” you’d probably earn a clip round the ear. Yet Juliet Nicolson in her book ‘The Perfect Summer’ tell us that this expression’s origin isn’t rude at all.
Because in 1911, with motoring in its infancy, cars were for the rich who could afford chauffeurs for their Rolls-Royces. And if one of these near extinct species was over talkative, then he would be instructed to ‘shut his trap’. This being the little flap between himself and the passengers compartment.
Mind you this was the least indignity that our automotive minion could suffer. For ladies annoyed at their directions not being heard above the engine would jab their driver in the neck with their umbrellas. But it’s ‘shut your trap’ we remember even if not the phrase’s origin. Proof then its not the meaning of words that is important – its their and our intention.