While waiting for Beth to finish with her work, Morty finds a horse inseminator. Morty asks Beth if he could do a part job at her horse hospital after work which she agrees to. During which he masturbates with the inseminator.
Rick's attempt to make a bioweapon to use against an underground race of
cannibalistic horse-people (the "Chuds") goes awry when he uses a barrel of horse
semen in his experiment which, unbeknownst to Rick, also contains
Morty's semen. The failed experiment results an explosion which unleashes a swarm of giant, mutated
sperm that begin attacking and murdering humans. Rick and Morty are sent by the president with a team of troops to destroy the sperm's nest. The team is killed, with the exception of Rick and Morty. The Sperm Queen uses Morty to create more sperm monsters before they are rescued by a friendly sperm Morty names Sticky. Eventually a plan is devised and set in motion by
the president to lure the mutated sperm with an enlarged, human
egg harvested from
Summer. However, unknown to everyone who contributed to the plan, the sperm originated from Morty. After Morty confesses the truth and everybody realizes that they are about to create a "giant
incest baby", the President orders his forces to defend the egg from the sperm at all costs. Rick, Morty, and Sticky are captured by the Chuds and are about to be eaten. However, the Chud king's daughter, Princess Poneta, reveals Rick got her pregnant. This leads the Chuds to help the humans in stopping the sperm. One lone "underdog" sperm, whom Morty befriended and named "Sticky", unexpectedly breaches the egg, fertilizing it. The President, who forbids outright destroying the egg for political reasons, instead has it launched into space. Poneta then gives birth to Rick's fowl revealing they are independent once born and leaves Rick. In the post credits scene, an astronaut is grabbed by Summer and Morty's giant incest baby. ==Production==