hang-up vs land mine

hang-up

noun
  • An unforeseen obstacle to progress; a hitch or delay. 

  • An emotional difficulty or a psychological inhibition; a complex. 

land mine

noun
  • A critical subject or situation with concealed or unpredictable implications. 

  • A piece of exercise device consisting of a pivoting tube attached to the ground to which a barbell can be fitted to lift it off the ground. 

  • A mine that is placed on land and designed to explode when stepped upon or touched. 

How often have the words hang-up and land mine occurred in a corpus of books? (source: Google Ngram Viewer )