And on the word shit, there is a long tradition in various world cultures of curse words being named on bodily functions. But you are missing the obvious in that "curse" words are such because they were originally thought to bring a curse on the speaker or recipients from whatever god-entity they believe in. I suspect this is a manifestation of (ancient?) society's methods of trying to control the fuck out of everyone and it is a meme burned in our consciousness quite deeply at this point. But all that makes the entire notion of curse-words invalid; if their meaning is that which we attribute to them then they are meaningless and therefore harmless. But with morality unable to escape the shadow of primitive, ignorant times, they continue to be "taboo"