Most everyone can whistle, but whistling through one's teeth is the crème de la crème of whistling--ultimate whistling, if you will. Well, guess what: you too can join the ranks of through-the-teeth whistlers. All it takes is a lot of practice and a little know-how. Read on to learn how to whistle through teeth.
Extend your lower jaw a little. Whistling through your teeth may make you look funny, but you can get a really powerful sound.
Pull back the corners of your mouth a little. Do not expose your bottom teeth, but you may expose your upper teeth if you wish.
Make sure your bottom lip is taut against your lower teeth. If you need help creating this tautness, you can press your index and middle fingers on either side of the mouth (on the outside of the mouth only, not inside the mouth).
Draw back the tongue so that it's about the same level of the lower teeth. Notice that your tongue is broader and flatter, leaving a small space between it and your teeth.
Inhale deeply, then blow, forcing air between the space left between your tongue and your teeth. Experiment by adjusting your jaw, the tautness of your lips and the position of your tongue until you make a sound. The sound may not be loud to begin with, and may resemble a tire losing air, but take heart; a whistle is close.
Keep practicing until the sound becomes both louder and clearer. Eventually, it will become that shrill, through-the-teeth whistle you aim for.