Opinions that a person might think is good/right, but are based on facts that can easily be proven false through common sense and actual facts. Mostly used by assholes, liars and ignorant people.
Portmanteau of the words "phony" and "opinion".
Person 1: "I simply love Leonardo DiCaprio. Did you know that he almost won the entire Oscars?"
Person 2:" Of course not, a single person can't win the Oscars because there are too many awards for one person to achieve."
Person 1: "No! I am right, look it up on Wikipedia!"
Person 2: "Well, that's just your phopinion, man."