a bubbly, gurgling flatulant emission created when an individual with excessive moisture in their asscrack, or possibly just a fat ass, farts. The sound of a bog fart resembles that of the bubbles created by organic decomposition in the darkest depths of a swamp, or perhaps by the boot of an intrepid explorer being pulled from an accidental step into a peat bog, hence the term. Such a fart could also be compared to the sounds created when a man has sexual intercourse with a woman of poor personal hygiene, commonly referred to as "swamp sex."
Neelsaw always has bog farts because he's fat and doesn't wipe his ass properly. He even goes so far as to put his shitty wipes in the trash can rather than flushing them, almost as if he grew up in, most appropriately, a bog.