Monkey business can involve a psychopathic hunt or control of victim or victims that can endure for years where the victims endure a steady decline of resources altogether and of their own health, becoming depressed and suffering constant harassment and pressure from various threats.
This interpretation of the dubious version of the concept, I think, to one end or another, is associated with the brown remains of a smaller person, typically a kid. You know, this may happen when you're exposed to psychopaths. They take their victim to some place where they do their freak stuff, reducing this (young) person to this brown, i.e., bloody by stark blood, burnt skin, dirtied by feces, lifeless, insidiously treated object! This goes for nothing less than torture and has some value to dubious people for "energy reasons"/"stratagems"/"efficacies of kind", so and so!
I'm telling you right now, beware of these idiots!!! More serious than this, it can't get!
Tortured abducted kid is found dead. It's probably the victim of monkey business. - Police report