Bongs are large, unnecessary smoking paraphernalia used by overzealous teenage stoners. Because smoking a joint is not enough, they decide to go down on this phallic tube like an enthusiastic auditionee for Chitty Chitty Gang Bang.
The word Bong in Thai means "Bamboo water-pipe for smoking shit". However, from studying anglo-Chinese cave paintings it has become clear that the history of the bong dates back to early 2nd Century BC. Taiwanese natives used Rigor Mortis Possum carcasses as a tool for smoking, as the entry passages to the animal created a comfortable seal around the makeshift tobacco cases. The smoke from the animal not only got the natives blazed, but it helped them coexist with killer acid-spewing wasps who also shared the island.
Since photos arised of Olympic swimmer Michael Phelps going down on a bong, sales have made a turn for the worse in the US. Looking like George Bush's genetically modified child and with the distant face to match, Phelps has helped to single handedly tackle the bong market.
In the UK, laws on Bongs used for Cannabis are strict. Although being caught in possession carries only a mild result (confiscation, £80 fine on second offence) finding a Bong on your person can make things much more serious.