When a morbidly obese person farts so hard that it travels up their back going in between each fat fold and ends at the base of their neck.
The sound can be mistaken for that of a family of ducks being run over by a group of cyclists or a running motorcycle half submerged in water.
Say Jill, did you hear that comical noise, i believe that guy over there just fatted. Yes Pete, he was obese
and he farted
so that means that he fatted, now he will have to change his shirt.