Throw a monkey wrench in
Meaning
To introduce a major problem or obstacle that prevents a plan or process from proceeding smoothly.
Origin
The phrase evokes the vivid image of industrial sabotage, emerging from the literal act of casting a heavy metal monkey wrench—a common adjustable tool—into the gears or moving parts of a machine. Such an act would immediately seize the machinery, causing catastrophic damage and bringing operations to a grinding halt. This powerful visual of mechanical disruption, likely practiced during periods of industrial unrest or by disgruntled workers in the late 19th or early 20th century, quickly became a potent metaphor for any deliberate or accidental action that derails a plan or process, effectively jamming the 'works' of any endeavor.
Examples
- The sudden budget cuts threatened to throw a monkey wrench in their carefully planned expansion project.
- Just when the negotiations were going well, a new regulation came out that threatened to throw a monkey wrench in the whole deal.