This is a term used when describing the necessity to form ones mouth tightly around the anus of another after that person male/female has ate every gas inducing ingredient. When the gas is released it is ingested and must be kept down until it becomes a fart again. This can be repeated as many times as one likes.
Look at the fine ass on that woman! Id sure like to Gastric Gulp on that for awhile!
Oh come on don't be a Gastric Gulping fool