1st the definition:

…So, when somebody said that an individual had “bats in the belfry” it meant that there was “nothing going on upstairs” (as in that person’s brain). To be BATSHIT CRAZY is to take this even a step further. A person who is batshit crazy is so nuts that not only is their belfry full of bats, but so many bats have been there for so long that the belfry is coated in batshit. Hence, the craziest of crazy people are BATSHIT CRAZY.

See Urban Dictionary for a full definition. 

Usage Example:

I thought Trump was a bit crazy, then came Biden, he’s batshit crazy. He said if you want to take on the Government you better have some F-15’s and Nuclear Weapons.

It was often said that Trump should not have the nuclear football.  At least Trump never threatened to nuke his own people. Biden is batshit crazy.

~ Recently converted to Republican from Democrat Veteran.

Admin note:

This is being posted because we will likely refer back to this post from time to time.