monkey wrench noun
plural ∼ wrenches [count] : a wrench that can be adjusted to grip or turn things of different sizes — used in U.S. English to refer especially to a large, heavy wrench with a long, straight handle
throw/hurl/toss a monkey wrench into
US, informal : to damage or change (something) in a way that ruins it or prevents it from working properly
▪ The storm threw a monkey wrench into their plans for a picnic. [=the storm ruined their plans for a picnic]
▪ The storm threw a monkey wrench into their plans for a picnic. [=the storm ruined their plans for a picnic]
