"shwag" is short for "shwiggity shwag" which was birthed from
the phrase "sliggety slag": a cute reference to slag bud.
"Slag bud" is marijuana that
has been highly compressed into bricks
(while still green). Heat and lack of ventilation
tipically cause plant decay and mold growth. Once dry, these bricks
(when broken apart) tend to come apart in large
look like the by-product of iron smelting(slag).