A person who is batcrap crazy is certifiably
nuts. The phrase has origins in the old fashioned term "bats in the belfry."
Old churches had a structure at the
top called a belfry, which housed the bells. Bats are extremely sensitive to sound and would never inhabit a belfry of an active
church where the bell was rung frequently. Occasionally, when a
church was abandoned and many years passed without the bell being rung, bats would eventually come and inhabit the belfry. 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 BATcrap CRAZY is to take this even a step further. A person who is batcrap 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 batcrap. Hence, the craziest of crazy
people are BATCRAP CRAZY. ( thank/thanks kbli)
It has been reported brain eating zombies protesting in Washington DC, one was quoted as saying " we are not only starving, we are asking the
FDA, to require labeling for those whom are batcrap crazy, warning "taste like batcrap",
FDA defended their policy position, "we here at monsanto don't believe in labeling what we put in anyone's
food"