A bong (also water line, billy, bing, or moof) is often a filtration device generally useful for smoking cannabis, tobacco, or any other herbal substances. Inside the bong shown within the photo, the gas flows through the lower port for the left on the upper port for the right.
In construction overall performance a bong is just like a hookah, except smaller especially more portable. A bong may be manufactured from any air- and water-tight vessel with the addition of a bowl and stem apparatus (or slide) which guides air downward to below water level whence it bubbles upward (“bubbler”) during use. To acquire fresh air in to the bong and harvest the past remaining smoke, a hole known as the “carburator”, “carb”, “choke”, “bink”, “rush” “shotty” “kick hole” or simply just “hole”, somewhere about the lower area of the bong above water level, is first kept covered in the smoking process, then opened to allow the smoke to be drawn in to the respiratory system.
The word bong can be an adaptation of the Thai word bong or baung, which refers to a cylindrical wooden tube, pipe, or container cut from bamboo, and that also refers back to the bong used for smoking.
Bongs have been in use through the Hmong, in Laos and Thailand, and over Africa for years and years. One of several earliest recorded purposes of the phrase under western culture influences McFarland Thai-English Dictionary, published in the mid 1940s, which describes one of the meanings of bong in the Thai language as, “a bamboo waterpipe for smoking kancha, tree, hashish, or even the hemp-plant.” A January 1971 issue of the Marijuana Review also used the term.