Just what are they smoking down in the Parliamentary Budget Office?

The normally conservative federal institution has done some highly unusual economic modelling based on the question: how much money could the Turnbull government raise if it legalised and then applied the GST to marijuana?

The federal government could raise $300 million a year in tax if it legalised marijuana.

The answer is about $300 million a year.

And that doesn't even include the increased tax toke – sorry, take – from the inevitable boom in sales of pizza and Doritos.