the last straw

1. The last in a series of grievances or burdens that finally exceeds the limits of endurance: “The management has given me nothing but trouble since I took this job, and now they've cut my benefits! Well, that's the last straw: I quit!” It comes from an old expression, “the straw that broke the camel's back.”

Idioms and Phrases

The final annoyance or setback, which even though minor makes one lose patience. For example, I could put up with his delays and missed deadlines, but when he claimed the work was unimportant—that was the last straw! This term is a shortening of the straw that broke the camel's back , which conveys a vivid image of an overloaded animal being given one slight additional weight. The expression dates from the mid-1800s, and replaced the earlier the last feather that breaks the horse's back .