afraid vs scared shitless

afraid

adj
  • Impressed with fear or apprehension; in fear. 

  • Regretful, sorry; expressing a reluctance to face an unpleasant situation. 

  • Worried about, feeling concern for, fearing for (someone or something). 

scared shitless

adj
  • Very frightened, terrified. 

How often have the words afraid and scared shitless occurred in a corpus of books? (source: Google Ngram Viewer )