butter wouldn't melt in (someone's) mouth

if butter wouldn't melt in someone's mouth, they look as if they would never do anything wrong although you think they would.

She looks as though butter wouldn't melt in her mouth but I've seen her fighting with the younger kids.

• lay open to
• lay out
• lay out something
• lay over
• lay someone low
• lay someone off
• lay someone open to something
• lay someone to rest
• lay someone up
• lay something at door
• lay something at someone's door
• lay something on
• lay something on someone
• lay something on the line
• lay something open to
• lay something to rest
• lay the blame on
• lay the blame on someone
• lay the blame on something
• lay the ghost of
• lay the ghost of someone
• lay the ghost of someone to rest
• lay the ghost of something
• lay the ghost of something to rest
• lay the ghost of to rest