Green’s Dictionary of Slang

yaba n.

also ya ba, yabba
[Thai ya ba, crazy medicine/drug]

a form of methamphetamine, orig. created by Nazi chemists during WWII, but particularly popular in Thailand.

[UK]Observer 17 Oct. 5: The so-called Nazi method of making yaba was first noticed in Thailand more than 30 years ago.
[UK]Guardian Travel 15 Jan. 3: Yabba, a kind of nuclear amphetamine which, if smoked in silver foil, will keep you going forever.
Associated Press 22 Sept. [Internet] But what may seem as harmless as candy is a new form of methamphetamine called ya ba, a Thai name meaning ‘crazy drug.’ It is said to be significantly more powerful – and dangerous – than the current club drug of choice, Ecstasy.