BUTTER WOULDN'T MELT IN ONE'S MOUTH

{informal} You act very polite and friendly but do not really care, you are very nice to people but are not sincere. * /The new secretary was rude to the other workers, but when she talked to the boss, butter wouldn't melt in her mouth./

{informal} You act very polite and friendly but do not really care, you are very nice to people but are not sincere. * /The new secretary was rude to the other workers, but when she talked to the boss, butter wouldn't melt in her mouth./