The word bong as meaning "device used for smoking substances" is relatively new to the English language. It was introduced in the early 1970s by Vietnam War veterans who borrowed it from the Thai noun baung, which referred to a type of bamboo instrument used for smoking hemp. Bongs were in use in South Asia for several centuries before that; it's thought that baung comes from an earlier word meaning "strip of wood". By the late 1970s, the term was in widespread usage. Bong also can denote a bell sound; that meaning traces to 1918 and is just onomatopoeic of the sound. Another definition that has recently emerged in the mountaineering world is "metal peg used for climbing", and that's also imitative, of the sound the spike makes when it's driven into stone.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.