a plum in your mouth
US /ə plʌm ɪn jʊər maʊθ/
UK /ə plʌm ɪn jʊər maʊθ/

1.
слива во рту, говорить манерно
an affected way of speaking, as if one has a plum in one's mouth, often associated with upper-class accents
:
•
He speaks with a plum in his mouth, making him sound very aristocratic.
Он говорит так, будто у него слива во рту, что делает его очень аристократичным.
•
Her affected accent sounded like she had a plum in her mouth.
Её манерный акцент звучал так, будто у неё слива во рту.