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.
New York Times: "ORGIASTIC FRENZY AS GUANO WILD-FIRE DRIVES WORKERS BATSHIT CRAZY"
by maxcct April 8, 2011
Word meaning "certifiably insane" Origin comes from the fact that bat feces contain an organism called Histoplasm Capsulatum that infects the brain of any host in which it infects and causes them to act psychotic.
The guy found out the paternity test results and went batshit crazy!!!
by medic1 August 12, 2014
The phrase came from Indian tribes who slept in caves. After long periods of exposure to the caves filled with "batshit"the Indians would start losing their minds. Some hyroglyphics illustrate people eating other humans including the face.
by Bat knowledge September 27, 2016
A way to describe someone of any gender who is crazy enough for observers to equate their speech or behavior to guano and its properties. (Runny, stinky, absolutely chaotically displayed, ect.)
That one is batshit crazy.

It's enough to drive me batshit crazy.
by Rain Kate August 10, 2021