The word 爆粗 is formed by combining 爆, meaning to burst or explode, which conveys a sudden outburst, with 粗, meaning coarse or vulgar, referring to offensive language. This creates a verb-object compound where 爆 acts as the verb describing the action and 粗 serves as the object representing the content, resulting in the literal meaning "to burst out coarse language" and the idiomatic sense of swearing or using profanity.