In this movie, people become zombies by repeating too many politically-correct statements. The few remaining free-thinkers fight for survival. The reason why the movie is called "Dickless Zombies" is because conformists remove the genitals of any zombie that is killed - the elements would degrade the clothing, which would result in the penis being revealed to any passerbyer. (No, there isn't any depiction of this removal on screen). This shows how stupid average Americans are.
