A plum in (one's) mouth British singular noun
Primally used in the UK to indicate the typical manner of communication from the high social class
Although she isn't from the high class, she can speak with a plum in his mouth, thanks to the careful teaching of his wise mother.
He always talks with a plum in his mouth, which makes people feel annoyed.
Used to describe someone who is good at persuading people to do or believe something
To argue with somebody
Used to allude that the last force, problem or burden which is seemingly minor and small causes a person, system or organisation to collapse or fail
Her husband's violent act last night was the straw that broke the donkey's back and she left him