It is my understanding it means to purposely "mess" things up or cause trouble so things to not go smoothly. Example- "Judy thinks she is a shoe in to get the promotion at work, but I am going to...
monkey wrenches are named appropriately because due to their dexterity they can reach places that we as humans can not.
To throw a monkey wrench (or spanner) into the works is to disrupt an active process, or to spoil things usu. by spoiling but also unintentionally.
no.
no they assasinate their enimeys. they just trow poo at people that dont feed them.