The guy holds out a cigarette-like object as he says this. It was obviously a bit of an anti-smoking message in the middle of the film. At least that is the way it always seemed to me. If it is going to be kept I really like the idea of just sticks. It does make it seem more like drug slang, and makes it seem less like it is trying to give the message that smoking kills.
I honestly don't see "You wanna buy some sticks?" any less understandable than "You wanna buy some death sticks?" I really think "sticks" is much more on par with typical real world drug names than "death sticks" is.