This is five fun things to do with a glass bottle. You don't need the bottle to be glass, but most glass bottles are the right shape to do these things.
Step 1: Whistle
This is hard to learn, but very loud once you get in mastered.
Put you thumbs on the bottle like in the picture. Put your mouth on the middle of your thumbs and blow. If it doesn't work, move your thumbs around a little.
Step 2: This Has No Name
Take a dollar bill or a piece of paper about that size and set it on the edge of a table. Put the bottle upsidedown on top of the bill. Pull the bill away quickly and the bottle should stay in one place.
Step 3: Shaker
Take a airsoft bb and put it in the bottle. Turn the bottle upside down and and start shaking. If you shake fast enough the bb should stay in the bottle.
Step 4: Laser Bottle
Pour water into the bottle. Go into a dark room with a laser and shine the laser on the bottle. It will light up the bottle and look cool.
Step 5: Instruments
This last fun thing could be used as a science experiment. Take two or more bottles and fill them up with different amounts of water. Than blow over the top of the bottles. The bottles with more water in them should make a higher sound. If you use different shapes of bottles, keep in mind that bottles with bigger openings should have a higher sound than ones with smaller openings. Although you probably couldn't play a song with this, it is still very fun.
Step 6: Have Fun!