Green’s Dictionary of Slang

bong n.1

also bhong, bongo
[Thai baung, lit. ‘cylindrical wooden tube’]

[1970s+] (US drugs, a kind of bowl-shaped water-pipe used for smoking marijuana (the specifics vary as to the maker); thus Aus.) bongineering, bongology, the construction of such pipes; bong hit, a puff on such a pipe.

In compounds

bonghead (n.)

a habitual smoker of cannabis.

In phrases

bong on (v.)

[1980s+] (Aus.) to smoke a bong.