fence = plasma membrane. it let's the players in and it has holes, so it could be semi-permeable.
the ground = cytoplasm. it holds everything together
the janitors who sweep up the dust after the game = lysosomes (they detoxify the cell)
players in the outfield = vacuoles. they transport the substances (softballs) back to the players in the inner field
umpire = nucleus. he calls the shots
the coaches = ER - makes the proteins
the players = golgi - modify the proteins