When people get angry or upset, a set of words may be used to express this displeasure. These "cross words" are meant to have an effect, either on the person uttering them or the recipient of them. Various bodily functions, genetic associations or religious blasphemies are used, sometimes interchangeably. The actual words matter little, except to possibly illuminate a darker aspect of the speaker's psyche. Is it rather a form of animal-like growling? Of primate howling? There must be more to it than that, for otherwise these "special" words could be replaced with any word, no matter how inappropriate. Or does it stem from childhood taboos on speech? I always told my children that "those" words were OK, if saved for the right time. "Don't wear them out - you might really need them someday!" They don't seem to curse (in my presence at least!) that much. It doesn't seem that religious training has too much to do with it, both pious and pagan alike use the same vocabulary.
Horsefeathers! I may never understand it.