Mod 80: Navi Sheker
I know that you didn’t mean it literally with all the halachic implications, but I think you should think twice before throwing this accusation around, even in jest.
False prophecy is a very serious sin. You wouldn’t accuse someone of idolatry in jest or adultery in jest. I believe this rises to a similar level. Just my humble opinion (for what it’s worth).
The Wolf