Double Puff Dragon

When you're smoking up with one of your friends and watching movies, the moment the last puff of the jay comes by it is taken by one of the two. When the joint is finished, and the person lets out a cloud of smoke, both of you think its done. The last one to smoke proceeds to stare meaningfully at the finished spliff, when all of a sudden that person lets out another billow of smoke through his nose. However, not just one, but TWO billows. THAT is the Double Puff Dragon.
The smoke resembles that of a dragon.