A polite way of referring to unsavoury use of the English language. derived from the impressions of stereotyped pirate figures, whom are viewed as being of lower social scale and hence more likely to us unsavoury English.
Similar usage to the phrase: "Pardon my French"
Person One: "Fuck you Fucker-head"
Person Two (Response): "Please, there is no need to use Pirate Words"