Fart - warning of the oncoming poop. Not a definite indicator of the arrival time, but a warning that it is approaching. Similar to a tornado siren. Innocent bystanders should be evacuated.
Fart "The Poo Siren has sounded, I think it is time we finish up this bike ride here soon. I can't be 100% sure, but this one could knock down a small town."
by Bearded Bandit September 22, 2012