a sly dog

a sly dog

Someone who, through cunning, devious, or dishonest means, achieves a fortuitous outcome. What a sly dog, he managed to get a copy of the test so he could memorize the answers ahead of time!
See also: dog, sly
Farlex Dictionary of Idioms.
See also:
  • (as) sly as a fox
  • sly
  • sly as a fox
  • (as) cunning as a fox
  • cunning
  • (as) wily as a fox
  • crafty
  • fox
  • (as) crafty as a fox
  • crafty devil