I'm amazed at the scope of scatological language employed by males, especially; not so much from a moral perspective as from a sense of imaginativeness.
Take the f-word. Nowadays, it's less often used to refer to performing the Rites of Venus (as it would be referred to in bodice-rippers) but as an intensifier or a randomly distributed expletive to be deleted by polite people when recounted in journals or newspapers. Or dropped when interviewers are least suspecting.
But there's a surprisingly wide scope of use of the old Anglo-Saxon word "shit." Yes, the French use "merde" as an exact translation; and the Germans weigh in with "scheisse." And a Frenchman may encourage another by MALPT ("shit to the thirteenth power!) and a German perv might watch scheisse movies (don't go there!)
They even press other species into the process. For some reason, this final product of digestion is seen as joyful when accomplished by equines ("happy horseshit), and as an exclamation of disbelief when the subject is a male of the bovine persuasion ("Bullshit!") When a person goes apeshit he is going into a rage or a highly agitated state. Chickenshit has a dual meaning: When something is chickenshit, it means that it is petty or insignificant (e.g., a chickenshit dress code in a high school). When someone is described as chickenshit, it means that he is cowardly.
Paul Fussell described chickenshit in the military: “Chickenshit refers to behavior that makes military life worse than it need be: petty harassment of the weak by the strong; open scrimmage for power and authority and prestige; sadism thinly disguised as necessary discipline; a constant 'paying off of old scores'; and insistence on the letter rather than the spirit of ordinances.”
But there's an interesting possibility with bat shit crazy. Bat shit, more politely known as bat guano, does often carry the fungus Histoplasma capsulatum which can have neurological consequences and result in the host contracting psychotic symptoms. This was most likely an accident in language, somewhat similar to the origins of the slur term redneck.*
Maybe there's a place in the psychiatric language to recognize this. If we call it bat guano psychotic, that ought to do it.