If you increase a camel’s burden straw by straw, eventually you will load him
one straw too many that his back will be broken. The phrase ‘the last straw’
refers to something that, although small in itself, comes after other
troublesome things and produces at last a feeling of being intolerable.

> Mr Jackson’s neighbours had very noisy children. He put up with it as long
as hi could, but the last straw was when the boy next door decided to learn to
play the bugle.

##### See also:

* The last drop makes the cup run over