1. the upward thrust of pants after a very powerful fart
or release of ass gases.
Background: My friend and I were sitting around when he had to pass some gas while wearing very loose fitting pants. The deep bass was only surpasses by the upward 'fluff' of the pants which settled back downward after the thrust of ass gas.
That guy had some powerful parachutin erruption, I'd say it almost broke through his pants.