Yaba (also Ya Ba or Ya Baa; "crazy medicine" in Thai) are tablets containing a mixture of methamphetamine and caffeine, often candy-flavored and brightly colored. This illegal drug is especially popular in Thailand, where it is imported from neighboring Myanmar. In recent years it has also been used by immigrant populations in the United States, and occasionally as a club drug replacing ecstasy.
Yaba tablets were outlawed by the Thai government in 1970; at the time they were sold at gas stations and used by Thai truckers to keep awake.