The last/final straw

ImageMeaning:

The last in a series of unpleasant or undesirable events that makes you unable to accept a situation any longer.

If an event that follows a series of bad events or experience makes you feel you cannot tolerate a situation
any more and finally decide to leave it or do something to change it,
you call the event the last or final straw.
People also call it the last/final straw that broke the camel's back.


Example:
The low salary and the demanding boss were bad enough, but the rude co-worker was the last straw.
(Then I decided to quit the job.)

I bought a car three months ago, but I had a brake and transmission problems.
Last week's engine trouble was the final straw.
(I decided to sell it or junk it.)