I've also heard this called a French pull.
To do a French inhale, you take a drag of smoke into your mouth (not into your lungs) and push it out of your mouth while inhaling through your nose. With a little bit of practice, you'll get used to the rate you push smoke out and the rate you inhale smoke through your nose, and will be able to adjust each to be equal. This can be done with any type of smoke, but thicker smoke (such as cigar smoke) usually looks better.
It always came easily to me, but many people have trouble with it. You can practice by exhaling, filling your mouth with water, and squirting the water out as you inhale through your nose. If you know how to circle breathe (you know, like Kenny G), it's very similar.
Usually, it's done so a flat stream of smoke floats gently out one's mouth and leisurely into one's nose, but it's easy to get carried away. In a still room, you can create some beautiful billows of smoke and gracefully peel them away into your nose. An excellent example of this is in Guy Ritchie's Lock, Stock, and Two Smoking Barrels, when Bacon enjoys a rather large joint.
Somewhat like this is the habit of snorting smoke rings I have a friend who will blow a smoke ring and just before it starts to lose its form, he sticks his nose nearby and inhales. The part of the ring closest to his face is quickly sucked into his nose, and the rest slowly stretches in.
briglass says ...don't you mean Freedom inhale?