My question is about the meaning which I'm not too sure. Can you also explain about the origin (roots) of this idiom...Literally, did the idiom come about because of the way camel minders beat the camels using straw or because bales of straw are loaded onto the camels till the animals cannot take it anymore???
I believe it came from an Arab saying/proverb. It was about overloading camels but not necessarily with bales of straw. The meaning of the saying in English is that one small insignificant thing has been added to someone's burden and that the result is that the person cannot or will not function in the expected way. It is often used when a person has been made angry by another by repeated insults or lack of consideration over a period of time - one final insult or inconsiderate act (the straw) then causes the person in question to blow up.