When you fart and a little bit or a whole lot of shit comes out.Can also have some quite humourous results..I will now tell you a story ....Once upon a time me, my cousin and his GF were having Macdonalds.My cousin told me (In hushed whispers) that he needed to fart really bad but didn't want his GF to hear.I told him to try and make it an SBD .Colin (my cousin) made a SBD but at a horrible cost....By the time we left the establishment it was on the floor.......I had to go back and clean it up....It was horrific.......................The moral of the story is....If this happens to you RUN!!! don't go back and clean it up...............RUN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Here are my helpful (Maybe) catergories.Cat1:Slight wet sensation...You got off easy... Cat2 :Spreads all over inside of boxers/briefs. If your going commando this could be a problem.Cat3:Soaks through boxers/briefs and wets inside of pants.If your going commando this is catergory 4.Cat4:Has soaked through to the outside of pants and has now left a big brown/green mark on back of them. Cat5 :Runs down leg (Really bad if your wearing socks or god forbid...a skirt! 0.0 ....) ...... Cat6 : An explosion (Example of it found in story).