Boorishly is how someone acts when the behaviour is boorish: they speak, laugh, or move in a rude, clumsy way, with little feel for other people. It is simply the adverb, “in a boorish manner.” You will meet it more in writing than in casual talk. Same warning as with boorish: it is about bad manners, not about being dull.

粗魯地；沒教養地。