Sez Robbie in the intro to his new blog, A Salute to Weed Carriers:
I'm not sure of who originated the phrase "weed carrier", but it pops up a lot over at The Mindset of a Champion, so I guess I'll credit Bol and Combat Jack with the term. It can be used in a number of ways, but the most appropriate is when it's used in reference to when a successful rap group gets their (usually far less talented) friends a deal.
Actually, I'm not really sure who invented the phrase "weed carrier" either, but I'll accept credit for introducing it to the world of hip-hop. I first started hearing it back in the day, probably from guys like Fitz and The Station, in reference to the basketball player Allen Iverson's entourage, who would sometimes get arrested for carrying his weed.
Anyway, definitely check out A Salute to Weed Carriers. I'll probably be contributing something to it the next time I get some free time, but there's already some cool shit posted there, including a story about Nas' many weed carriers and an inspiring tale of one rappers journey from weed carrier to weed owner.