tonk · noun1
Origins are unknown, but definitely predate the use of metal flashlights, contrary to the most quoted description of origin. It is probable that the origin relates to Chinese immigration, as the first law to restrict immigration from a particular country was enacted in 1882 to limit the numbers of Chinese coming to the United States. It is said that many of the illegal immigrants made their way to the US via the Gulf of Tonkin area of what is now Vietnam. It is also possible that the term is related to the Chinese "tong" mob.
tonk · noun2
Compare Tagalog tong-its, Ilocano tong-it, Pangasinan tung-it.
tonk · interjection, noun, verb3
tonk · noun4
Alteration of tank.
Tonk · noun5
Contraction of Tonkinese.
Etymology from Wiktionary, CC BY-SA 4.0.