Use this piercing whistle on strangers at your own peril.
You will need
Step 1 Wash your hands Wash your hands.
Step 2 Shape your lips Stretch your lips over your teeth, covering them completely.
Keep your lips relaxed.
Step 3 Choose a finger style Choose a finger style. Use your index fingers, middle fingers, or pinkies and keep a small gap between the tips.
Step 4 Position fingers Position your fingers between your lips so that they are in the center of your mouth. Extend your fingers into your mouth to the first knuckle and point the tips toward the back of your mouth.
Step 5 Position the tongue Flatten your tongue to the bottom of your mouth. Hold the tip a centimeter behind your lower gums.
Step 6 Whistle Blow so the air travels over the top of your tongue and over your bottom lip through the gap in your fingers. This will produce a high-pitched whistle.
Step 7 Practice Adjust your fingers, tongue, and lips. Practice makes perfect.
In theater, it is considered bad luck to whistle backstage.