Think it came from “bats in the belfry”.

This and this have some interesting information.

I think it comes from the phrase “bats in the belfry”, but people who go into the caves to collect bat shit (it is actually called ‘guano’ & it makes an excellent fertilizer) warn that they have to wear masks in order to get the ‘guano’ out. They have to wear masks because the guano is both musty & dusty, & if they do not wear a mask, it can lead to hallucinations. So, ere-go – you have “bat-shit crazy”.

@Linda_Owl “Ere-go”. I kind of like that.

@syz Great links. Thanks

@Linda_Owl Don’t they have to already be bat-shit crazy to go into caves to get bat guano?

Bakkeskite Crasie!! I Like it! Thanks @syz

@ETpro Guano is actually used as a sculpting medium. You can make bowls out of baked batshit.

Just a random thought, could it have to do with the fact that rabies is fairly common in the bat population and has been known to be transferred to humans? Is the crazy part more to do with the rabid, foaming at the mouth, psychotic symptoms of rabies?

I don’t know.

@Seek_Kolinahr OK, but I’m still not aching for a job mining the stuff.

Well, @ETpro , I think the ‘miners’ of the guano (bat shit) do not have very many alternatives to earn a living other than mining the guano for fertilizer. It is something that they have to do, in order to survive. I think, that if they had a viable alternative, they would not be ‘mining’ the guano!