These are the rules of the game:
You may say what you like
provided it is not serious.
You may say something serious
if your tone is flippant.
You may say something flippant
in a serious tone.
You may even say something serious
in a serious tone,
so long as you exaggerate just enough
to show that you do not mean it,
or to imply that you would mean it if ....
(without supplying the condition,
even in your own mind).
If you mean what you say
you must not let anyone know that you mean it.
If you say something you mean,
and if it becomes known that you mean it,
it is no longer the same game.
It may not even be a game at all.