This thing is part kazoo, and part whistle. It is harder to play than it is to make, but it is one of the simplest musical instruments you could ever make.
To make it - cut a length off a normal drinking straw, flatten one end and cut it to a point (with about a 7mm taper). That's it!
to play - the pointed end sits inside your mouth, held gently and partly flattened between your teeth (with the pointed section clear of your teeth) - then blow gently throuugh the straw. If you have it positioned right, it will play with a sound slightly similar to a kazoo