or you could:

1. cut a two liter in half.
2. With the top part of the bottle( with the cap ) place it in a big thing of water. bucket whatever.
3. place alluminum in bowl and punture holes. put weed in.
4. Light bowl while pulling the top part of the two liter slowly out of the water. But make sure that the bottle is still in the water just a little bit!! you dont wnat to smoke to exscape.
5. take the alluminum off and suck! Just make sure not to suck too hard or water will get in your mouth.

Ok yea it's the same thing as what this person ahead of me said but i think i just explained it a little bit easier, thats all. This does suck your weed down, but you wont believe what a massive hit you'll get!!!