A joint with the tip rolled into a point and put into a bong bowl piece. The bowl piece is then packed with weed around the joint to create more of a seal. It is called a Russian time-bomb because instead of water, vodka is being used in the bong. The joint is then lit and smoked down to the bottom. It then ignites the packed weed with the current burn, thus making it a Russian time bomb.
Two people smoking
Guy#1: Wanna smoke?
Guy#2: sure lets make a Russian time-bomb!