You have to shake the carton before drinking it — the settled sorghum solids are exactly what gives the beer its thick, porridge-like body.
Chibuku is an opaque, thick beer brewed from sorghum and maize, sold unpasteurized in paper cartons or plastic containers so fermentation keeps going right up until you drink it. It's cheap, sour, and sold everywhere from township shebeens to roadside stalls across Zimbabwe.