Simpson Flies Share definition Flag Small flies that infest an office setting due to rotting banana peels or other items left in trashcans or desks. For godsakes... these Simpson Flies are all over the place. Check the trashcans. Simpson Flies by jimmy bloughtou February 21, 2009 0 0 Get merch Get the Simpson Flies mug. Buy Now — $32.95 See more merch