when I lived in Wichita, the tiny local zoo had a Celebes Macaque(called Charley) who hated people and would poop and pelt! His aim was pretty good, too. They finally put a finer mesh wire around the lower part of his cage, which 'reduced' the effect. It was for awhile a form of entertainment for some folks to bring unsuspecting friends to the zoo soon after feeding hour and tell them to "call out to that big monkey on the end"....then stand WAY back.