butter won't melt (in one's mouth)

butter won't melt (in one's mouth)

Said of one who appears innocent, modest, or reserved in certain company, when in fact one may have the opposite demeanor. Sure, he looks as if butter won't melt in his mouth when he's around people he doesn't know, but stay a while and you'll see what he's really like. Samantha always affects this demure, butter-won't-melt expression on her face whenever she wants something from you.
See also: butter, melt
Farlex Dictionary of Idioms.
See also:
  • drive (one) out of office
  • force (one) out of office
  • force out of office
  • give (one) (one's) head
  • give head
  • give somebody their head
  • give someone their head
  • cooking for one
  • 1FTR
  • as one door closes, another opens