English Idiom - A Wrench in the System
Today's idiom is a wrench in the system. A wrench is a tool. Usually we think of tools as helpful things, good for building or fixing things, but a wrench in the system is actually a negative phrase. Imagine you have a big, complex machine with lots of gears and moving parts. Then imagine someone puts a wrench in the middle of those moving parts. This will cause big problems for your system, right? That's what we mean when we say a wrench in the system: it's a problem that causes a big complicated plan or system to break or fail.
We had our whole vacation planned out, but when we got food poisoning, it really put a wrench in the system.
If the new client won't agree to this contract, it will really throw a wrench in the system.
When they lost a major funder, it threw a wrench in the system for the new startup.