When your fart opens your anus releasing a wad of air while producing no noise.This fart can either be stinky or have no smell at all. If your stomach hurts than your fart will be hot and smelly.
I just farted and it was open-anus. My stomach hurts..did you smell it?
A flapping anus fart where some shit scud is released and gives your underwears a scud streek which resembles the look of a skid mark of a bicycle.
I couldn't hold it in so i scuddered in my pants.