title_body: If I'm in a rush, can I simply use raw ground coffee like instant coffee?
upvoted_answer: It boils down to taste - some people even chew whole beans. 
  
  Safety-wise there are no concerns1 and the method you propose is not unheard of, it goes by the term "Cowboy coffee" and others. Some preparation methods even quickly boil the grounds and water (Turkish coffee), other sources warn against pouring boiling water over your grounds and suggest letting the water cool a few degrees first.
  
  It is up to you to decide whether you like the grainy residue you might taste if you don't let the grounds settle enough before drinking.
  
  So, go ahead and do a taste test. You can always pour your coffee through a sieve or use the leftovers for drip coffee. 
  
  
  
  1 There is some discussion whether the slightly higher content of coffee oils compared to filtered matters healthwise, but that's a very vague subject, IMHO. Other brewing methods bring more oils as well.