When you really need to go for a shit and it suddenly catches you off guard. You have to stop everything you are doing, even if you are in the middle of a converstion with someone. you then run to the nearest toilet at the suprise of anyone watching. as you run, you uncontrollably fart, suprising even yourself! but often enough it is funny for all involved, it depends how well you know the witness
"i was rarting all the way to the toilet"