by Kate Asbury Larkin
Could’ve, would’ve, should’ve
Could’ve, would’ve and should’ve are contractions of could have, would have and should have, respectively.
Never, and I do mean NEVER, should you say (or write) could of, would of or should of. I cannot think of a single time “of” would correctly follow could, would or should. Not a one.
I have it on good authority that people have been unfriended on Facebook over this major pet peeve. That should of never happened. 
#oops
