This is a clear, easy to follow instructional video on how to whistle loudly with your fingers! This is the two-finger method, which is easiest for beginners. First put your tongue to the back of your mouth, and slightly curl your lips inwards. Using both hands with two fingers, place the tips in your mouth on, resting slightly on your tongue. Make sure your fingers just have a tiny bit of space between them; and then blow! This should make an extremely loud whistle. To practice, you should experiment with your finger positions, start with them slightly further apart from each other, and gradually while blowing, move them together, until they are at just the right distance apart for the whistle to sound.