The adjective 'batshit' (almost invariably premodifying the noun 'crazy
') derives from the fact that the guano of certain bat species, when smoked, vaporises as a potently psychotropic
narcotic. The word entered the popular consciousness after one of several dozen guano collectors dropped his torch, igniting the batshit (which, as a fertiliser, is flammable) swathing every surrounding surface. The fire spread rapidly, but all the workers managed to flee in time - having, however, inhaled a considerable quantity of the smoke. The resulting deranged rampage
made the international news, and "bat-shit crazy" was used in the New York Times headline. This coinage by the relevant subeditor seeded the general currency of the term, consolidated by a brief outbreak of the use of guano as a recreational drug, before even the most hardcore druggies
concluded that it was just too batshit crazy.