Larry, cool experiment
I don't think you will persuade Fred to blow on a pipe though hahaha.. I've confirmed your experiment by blowing on the manometer tube the same way you've described and it does in fact read a negative pressure
So yes, on a larger scale such as with a chimney, the same rules apply.
Your experiment may be easier to illustrate with a small flat piece of paper and a paper towel tube since a ping pong ball may be too heavy. The paper should stay put to the bottom of the tube while you blow across the top.