I've found this phrase in a game or movie. Don't remember now. What does it mean? Is it some kind of idiom?
The expression is most likely a variation of the idiom
to put/throw a spanner in the works
It describes the act of sabotaging or hindering a plan or project. The origin is rather obvious in this case if you think about, for example, throwing a wrench (AE) or spanner (BrE) into the spokes of a turning wheel.
The origin is "throw a monkey wrench into", see http://idioms.thefreedictionary.com/throw+a+monkey+wrench+into