Make water drop sound with mouth
Description: There is a cool way to make a drop of water sound with your mouth
Pucker your lips together as if you are going to blow air. Then pull your tongue back and thrust it towards the front of your mouth to blow a quick bit of air out.
Now at the same time your tongue is forcing air out, flick the side of your cheek. This creates a slightly higher pressure difference in your mouth and just enough to create a slight whistling sound.
Pull your lips back just a little bit to change the sound of the whistle.
Result: If done right you will hear what sounds like a water droplet.