There's no such legitimate product as 'cocain beer' in the legal market. If there is a so - called 'true story' about it, it might be related to illegal drug - laced drinks in the underworld or some very dangerous and unethical practices. But this is not something that should be associated with normal beverage production or consumption.
If there is a 'Cocain Beer True Story', it could be a story of how the law enforcement agencies discovered and stopped the production or distribution of such a dangerous concoction. Maybe they got a tip - off about a group trying to create this illegal 'beer' with cocaine in it. Law enforcement would then have to take steps to ensure public safety by shutting down the operation, arresting those involved, and making sure no such products reach the public.
The 'Cocain Bear' is based on a true story. In 1985, a black bear was found dead in the woods in Georgia. It had ingested a large amount of cocaine that had been dropped from a drug - smuggling plane. The bear's overdose on cocaine led to its death. The movie based on this event takes some creative liberties but is rooted in this strange real - life incident.