a trick done using the smoke from either a cigarette, or a joint. One inhales through the mouth, exhales most of the smoke, but inhaling the exhalation through the nose, and finally exhaling everything through the mouth again. It's a bit tricky, so you might want to practice before trying to show off your skills in public, thus making a fool of yourself.
Man, I've been trying to french inhale forever, and finally got it down. My sinuses are wrecked!
a trick done with inhaled smoke (presumably of a cigarrette, or joint). It involves sucking smoke from the cig into the mouth without inhaling it completely, then opening the mouth and pushing out the smoke with the tongue while inhaling it through the nose.
i thought french inhaling was cool until i did it and my sinuses felt like shit