fart preview

Refers to any occasion when you feel a large bubble of gas "transfer" or "travel" from the upper part of your colon to a position somewhat lower down, but without actually exiting from your butt immediately. This gastronomical "heads up" can be extremely useful in allowing you to both adequately prepare for the eventual "eruption" and hopefully prevent any disasters/embarrassment from said expellation, since it not only notifies you that a sizable fart is imminent, but it also enables you to (1) judge the approximate size/intensity of the upcoming whizzpopper and thus determine whether you should hastily change locale to avoid offending others' ears/noses, and (2) predict what **type** of fart ("dry" or "wet 'n' messy") it will likely be, so that if necessary you can rush to the bathroom, shed your pants and underwear like they're on fire (if they aren't already smouldering from repeated extra-spicy-chili farts!), or take other appropriate steps/precautions to lessen your chance of soiling both yourself and anything else that your butt happens to be in close proximity to, such as a chair, mattress/bedclothes, someone else's lap, etc.

The loud farts that always come to let you know you need to take a shit. The magnitude of these farts ofter will indicate or "preview" how retched the shit will be.