Oh, geez, my son does the same thing! Only he doesn’t scream that he needs to blow his nose. He just does it! Our rule is ‘Do not blow your nose into the air! Get a Kleenex!’
I am the Meanest Mommy in the Whole Wide World. I am forced to make rules & observations that I never knew would be necessary before I became a parent.
Rules by the Meanest Mommy in the Whole Wide World 
Oh, geez, my son does the same thing! Only he doesn’t scream that he needs to blow his nose. He just does it! Our rule is ‘Do not blow your nose into the air! Get a Kleenex!’