Meaning of “butter wouldn't melt in sb's mouth” in the English Dictionary

british dictionary

"butter wouldn't melt in sb's mouth" in British English

See all translations

butter wouldn't melt in sb's mouth

used when someone looks as if they would never do anything wrong, although you feel they might:

Tommy looked as if butter wouldn't melt in his mouth.

(Definition of “butter wouldn't melt in sb's mouth” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)