cough up vs plop down

cough up

verb
  • to pay, disburse 

  • to hand over, give. 

  • to expel from the lungs, throat, etc. by coughing 

  • to lose a competition by one's own mistakes, usually near the end of the contest 

  • To spill, to fumble 

plop down

verb
  • To pay. 

  • To sit or lie down heavily and inelegantly. 

  • To put down (something) in a heavy way. 

How often have the words cough up and plop down occurred in a corpus of books? (source: Google Ngram Viewer )