How to whistle really loud with no fingers
It made me
giddy 
"Surprising discovery."
How I did it: I ride bikes and I like to air guitar. The process of deep exhalation and making the pretend sound of a guitar was the serendipitous combination needed to discover how to do the loud whistle.
Basically, just make the Blue Steel face and keep your jaw tucked up so your teeth are like a bulldog. Exhale hard against your top teeth. Eventually will find the whistle you are looking for.
