Is this sentence natural?
(somone's mouth is wide open)

If I say;

You'll catch a fly!

Question

Is this sentence natural?
(somone's mouth is wide open)

If I say;

You'll catch a fly!

Answer

It's not something that we would say.

Answer

I would say, "Are you trying to catch flies or something? For the love of God, close your mouth. You look like you're retarded" But I think that I'm not as genteel as you, Pelin!! Ha, ha.
In summary, your sentence would be perfectly well understood in my corner of the world.
Dave