gravity bong:
okay, you have to do it, so simple. get a 2l bottle and cut a hole in the bottom of it, and cover it up with a finger, and fill it with water.
over the top of the bottle put some foil over the mouth, and pierce it with a pin or something really fine.
now put some weed or hash or whatever onto the top of the foil, and light it.
take the finger off the hole at the bottom and keep the weed lit. smoke should fill the bottle. once the bottle is out of water inhale the smoke!
please note tho, its a two man job.