Stress/shwag is also a slang term for low-grade weed. Stress can be discerned from higher grade weed by the following distinctive characteristics:
It will look and feel old and dry.
It won't look as fresh and green as mids or chronic.
It exhibits a rather insipid and unpleasant taste when smoked.
It's cheap as hell.
Most marijuana connoisseurs prefer chronic over mids or stress but there are some bud smokers who prefer the milder high induced by stress or mids(mid grade weed between stress and chronic). If you experience symptoms of high-anxiety or paranoia when smoking dank herb, you may want to try stress instead, it could also save you a lot of money as it is exponentially cheaper. However, many smokers complain of headaches, fatigue and stiffness due to smoking stress(giving aptness to the name).
The poorer quality of stress relative to chronic is due largely to the punishing abuse the herb is put through during it's preparation and distribution. Stress is usually grown in Mexico or Columbia by drug lords running large smuggling operations and care little about the quality of their weed. Most kids living in middle-class suburbia will never see stress in their lifetime. So, there is some truth when the government says "Smoking weed supports terrorism." But a more accurate statement would be "smoking bad weed supports terrorism." So just play it safe, smoke the chronic!