Bong is an Asian or Hindu table top vase. It makes for a lovely display venue for flowers or other decorative or fragrant foliage. It can be ceramic, glass, plastic, really any type of material. Some have elaborate graphics on them to make them esthetically pleasing, with some US made models having a more "modern art" type feel with tubes and such protruding at various points.
You simply place a liberal amount of water into it, in the bottom reservoir. Then you take your foliage and place it into the "cup" or, if larger, "bowl" shaped receptacle. This receptacle is sometimes close to the base (not to be confused with bass) and attached to a removable tube (called a slider).
If using foliage that generally grows in warmer climates, and you wish to preserve their usefulness for as long as possible, it is recommended that you carefully induce flame from a lighter to the "bowl" area, but be careful not to burn the foliage. If this does happen, (burning of the foliage), you can quickly remove the "slider" and use some sort of suction device or, if you have none, just use your lungs to remove the smoke from the "chamber". Take care not to inhale this smoke! Several people "never inhaled" it and became prominent members of society.
With the Hindu version, the receptacle is usually affixed atop the chamber, and they also have several tubes attached to allow more people to assist in the smoke removal, seeing as the receptacle (bowl) is usually quite large.
In either case, the water in these lovely vases should be changed, with the frequency depending on how many different "displays" you have used and how many times it was inadvertently set ablaze.
It is recommended that, were you to spill this water on a rug or piece of furniture, or even, god forbid a beloved pet, that said item just be discarded. It CANNOT be cleaned!