Do you know what "finish up a cook" means?

I'm a native born American and, yes, I know some drug slang but I've never heard this before. 44 Indian convenience store owners in rural Georgia are now facing drug charges because they claim they didn't know either (it means cook up methamphetamine). They sold chemicals that are used to make methamphetamine to undercover agents who, when purchasing the chemicals, said they were going to finish up a cook. I don't have much time to comment on this but a few thoughts come to mind:

1. Drug law enforcement may have reached the point of diminishing returns long ago.
2. This gives an incentive to police to be as obtuse as possible when they are trying to bust people for conspiracy. If they had said "I have to move $1000 worth of speed by tomorrow" that would be one thing but, of course, it is so direct they would risk not being able to complete the sale (and not being able to press charges).
3. The legal system does not have a lot of protection for foreigners not familiar with local culture. Juries often have to base decisions based on what "reasonable" people "should" do in certain situations which, of course, can vary greatly from culture to culture.
4. If these guys are all convicted (the American Civil Liberties Union is filing a claim of racial bias in these cases) it suggests there is an obligation on the part of immigrants to be familiar with local drug slang. The Dutch have started to distribute videos of nude women and of homosexual men kissing (among other things) to potential immigrants to prepare them for life in the Netherlands. Maybe the U.S. should do the same: make a video discussing all the drug slang commonly used interspersed with clips of junkies shooting up and crack-heads taking hits.