out to lunch vs round the bend

out to lunch

adj
  • Away eating lunch or for a midday break; especially, away from work or a job. 

  • Clueless, inattentive, or careless. 

round the bend

prep
  • Crazy, mad or insane. 

  • Close to or in close proximity to another location. 

How often have the words out to lunch and round the bend occurred in a corpus of books? (source: Google Ngram Viewer )