crazy like a fox vs slippery

crazy like a fox

adj
  • Behaving in a foolish, frivolous, or uncomprehending manner as a ruse for concealing clever deeds or deeper intentions. 

slippery

adj
  • Evasive; difficult to pin down. 

  • Unstable; changeable; inconstant. 

  • Of a surface, having low friction, often due to being covered in a non-viscous liquid, and therefore hard to grip, hard to stand on without falling, etc. 

How often have the words crazy like a fox and slippery occurred in a corpus of books? (source: Google Ngram Viewer )