From The Art and Popular Culture Encyclopedia
In language, dysphemism (from the Greek dys δύς "mis-" and pheme φήμη "reputation"), malphemism (in Latin malus "bad"), and cacophemism (in Greek kakos κακός "bad") refer to the usage of an intentionally harsh word or expression instead of a polite one; they are rough opposites of euphemism.
While "dysphemism" or "malphemism" may be either offensive or merely humorously deprecating, "cacophemism" is usually deliberately offensive. The term "orthophemism" has been offered to refer to a neutral name or expression.
Some humorous expressions can be either euphemistic or dysphemic depending on context because terms which can be dysphemic can also be affectionate. For example, pushing up daisies can be taken as either softer or harsher than died. Such variance can also be cultural; for instance, "twit" is a dysphemism for "idiot", but in British English is nearly always a humorous or affectionate term.