I don't think it means what you think it means.
Seriously– this is one of those products where I don't know how it made it all the way out of product development and through focus groups and the graphic design and packaging department, and not ONE PERSON ever said "Hey, you know what? A whippet is something I did when I was following the Dead back in the day, man!"
Seriously, I think the word "Whippet" is dead, with the possible exception of referring to the dog. "Pure Chocolate Whippet" just sounds to me like you would eat chocolate, then grab a tiny can of nitrous oxide and inhale.
Because that's what a whippet is, teenagers in the audience. It's a tiny can of nitrous oxide that you inhale and that makes you high.
