similar to diarrhea, occurs when one has eaten incredibly large amounts of fiber- far larger than the daily recommended amount- in a day's time and thus experiences excessive defication and gas as a result.
"Dude, are you okay? I heard terrible noises coming from in there."
-"Yeah, I'm fine. I had a ham sandwich on whole wheat, a cheese sandwich on whole wheat flat bread, 4 fiber loaded snack bars, some almonds, and a footlong sub on whole wheat today. It was some epic FIBERRHEA, but I feel awesome now.