Hops and Cannibus are related.
I've heard of a beer garden where they serve the house brew through a specially designed tap where the Hop-less house beer is filtered, just before it leaves the tap, through Hops; giving it the freshest hoppy taste. Maybe the same could work with cannibus. Surely it is not very efficient, but on a large scale (like a beer garden or a busy micro-brewery) it could work. I'm imagining, in the holding tank before bottling, the beer could have hops and weed soaking in it. The small amount of alcohol should strip off some of the THC and such. The large amount of weed required may make this cost prohibitive, but it could be either repeated or the cannibus could be dried and made into a tincture to fortify subsequent batches.