Colloquialisms
When I talk about my emigration to America I mention that the first thing I did was learn the language.
Which always raises a chuckle.
But when I am marketing to an audience, when I am trying to close a sale, when I want someone to inherently believe in my words, the last thing I want is for my audience to be distracted by an unfamiliar idiom (“as useless as tits on a boar hog” not “taking coal to Cardiff (or Newcastle)”), an odd pronunciation (“‘erb” not “herb”) or a curious spelling (“color” not “colour”).
Language is a tool.
An odd pronunciation or curious turn of phrase can be as powerful as dropping the word “Fuck” in to the middle of a sentence.
Learn to use your tools effectively.