Originally, a scientist hired by the Tobacco Institute to refute the findings that tobacco use resulted in cancer. Generally, it has expanded to mean any scientist paid by a moneyed interest to refute a scientific consensus or to create a false appearance of disagreement within the scientific community.
A form of snuff for all the fucking pussies out there. It's like taking a tiny ass dip and putting it in a bag. They are great to chew in school if you don't wanna get caught, but it's better to be a real man and pack yourself a big ole' dip of cope or skoal than to be the ultimate pussy.