In British slang a box means a Kilo of Cannabis.
It comes from where the grower packs the bulk product into a vacuum bag to eliminate odours and conserve space with slight compression, and then proceeds to pack the bag in the Box.
Person 1: "Sosa was moving Bare boxes of loud around the midlands ever sinceback in the day"
Person 2: "Dem crew is Peak, say Nuttin"
The trick ass bitch outside the club "The Gate" took attitude with me so I decided we needed to box to settle things. I laid her out on her fat shit-talking ass!