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There is a limit to everything. We can load the camel with lots of straw, but finally it will be too much and the camel's back will break. And it is only a single straw that breaks its back - the last straw. This can be applied to many things in life. People often say "That's the last straw!" when they will not accept any more of something.
There are a Spanish phrase and a Chinese phrase which have a similar meaning to the subject proverb and they are "La gota que colmó el vaso” and 忍无可忍 respectively

大家都知道,骆驼是非常强壮的动物,一般来说,一只骆驼可以运送很重很重的货物。但是,要是你不断往它背上加东西的话,这只骆驼到了一定程度就会达到它所能承受的饱和点,那怕再多加一根稻草也会使它承受不了而垮台。
Examples
  • You broke a lot of rules and I tried to put up with you. However, stealing money is the straw that broke the camel's back. You are fired!
  • Rompiste muchas reglas y trato de aguantarte. Pero haberte robado el dinero es la gota que colmó el vaso. íEstás despedido!
  • 你多次犯规,我已容忍你,但是挪用公款,我忍无可忍,我现在开除你。
  • You have been rude to me all day. I've had it. That's the last straw.
  • Has sido muy maleducado conmigo todo el día. ¡Me harté! !Esto es el colmo!
  • 你一整天对我不客气,我受够,忍无可忍!