How to make the perfect G.B.
1. Get yourself a clear 2 liter
2. Cut off the bottom where the tapered part meets the cylinder.
3. Find a coleman water cooler, similar to the giant ones teamates dump on the coaches head after a victory.
4. Find a small socket wrench.
5. Slightly melt the cap and then insert the socket wrench piece in the center but keep the square part of hte socket up.
6. Fill the cooler with water
7.place a ping-pong ball in the water, then put in the 2 liter bottle.

And there's the best damn Gravity Bong you could ever ask for.
Also water pitchers are nice. Try to find one that fits sort of snug around the 2 liter. The tighter the fit the better. It provides much better suction and push.
"Live like you'll die tomarrow. Dream like you'll live forever"