cooker

This is a derogatory term, the equivalent of nutter.  It has been applied to the far-right extremists who believe in conspiracy theories and who are anti-vaxxers probably because they think it is a government plot to get at them.  Until recently we thought that this small group in the community created a lot of noise but were ultimately harmless and so cooker had a dismissive feel to it.  Just a bunch of cookers.  But now, with the recent shootings in Queensland, we are sadly aware of what such extreme beliefs can lead people to do.

There is a suggestion that cooker used in this way is a new application of the term that existed in the drug subculture for the person who cooks in a meth lab.  The notion was that the cooker sampled regular amounts of what he cooked, so he was generally off his face.  Cooker was then used for anyone whose behaviour seemed erratic, as if drug-influenced.