Aliens!!! is the final episode of Back at the Barnyard.
Otis orders a satellite dish online in order to watch monkey boxing from Rio. Mrs. Beady sees this and believes that he is secretly signaling Aliens. Otis finds out and tries to prank Mrs. Beady with a fake alien invasion broadcast. This broadcast is sent to real aliens who are attracted to Earth and plan to conquer and destroy the planet. Otis tries to stall them while he figures out their weakness.
- Chris Hardwick as Otis
- Jeffrey Garcia as Pip
- Leigh-Allyn Baker as Abby
- Tino Insana as Pig
- Cam Clarke as Freddy
- Rob Paulsen as Peck / Ring Announcer / Armadillo / Alien #2 / Stomach Alien
- Wanda Sykes as Bessy
- Maria Bamford as Nora Beady
- Steve Oedekerk as Nathan Randall Beady III
- Fred Tatasciore as Farmer
- Daran Norris and Kevin McDonald as The Aliens
- Jim Meskimen as Goraldo
- S. Scott Bullock as Alien Announcer
- Maurice LaMarche as Captain Alien
The episode begins with Otis ordering a satellite dish in order to watch monkey boxing from Rio. Mrs. Beady sees this and believes that he is secretly signaling Aliens. Otis finds out and tries to prank Mrs. Beady with a fake alien invasion broadcast. This broadcast is sent to real aliens who are attracted to Earth and plan to conquer and destroy the planet.
When the aliens arrive, they meet the animals and don't believe that the broadcast was a prank. They even think that Otis is an actual alien due to the "tentacles on his stomach" which were actually just his udders. The aliens begin to plan their conquest of Earth while Otis plans on destroying them.
Otis throws a party for the new conquerors and tells Pig to put explosives in the cake. The aliens eat the cake and explode. Unfortunately, they are indestructible, and the animals fail at their attempt to destroy them.
At the party, the alien leader develops romantic feelings for Bessy, he wanted to marry her, but then Pip got jealous and kissed Bessy. The main alien shot Pip with a freeze ray, but then Bessy got mad and threw a glass full of milk at him. The alien's arm then started to dissolve. That is how the animals learned about the aliens' vulnerability to milk.
While the aliens went to summon the rest of their fleet to conquer Earth, Otis and the rest of the animals prepared to battle them. They made "fake udders" for the non-cows, and milk blasters, which were squirt guns that attached to their udders. Otis even gave some of his milk to the animals that couldn't shoot it themselves.
During the milk battle, Abby gets shot down first, then Otis growls at the alien sho shot her. Bessy shoots the alien captain on the arm, Freddy and Peck get shot down, then Otis gets shot directly in the udder with an energy blast. He then fights the captain alien and loses by getting thrown into a tree. While the Aliens were about to defeat the animals, Otis asks bessy to reattach his blaster to his udder. Bessy says she has a better idea, and she squeezes Otis's udders and his rich creamy milk rains down on the aliens; dissolving them.
- This is one of the four episodes not to use the regular intro.
- Bingo has a cameo in the opening. In fact, one of the monkey boxers is named Bingo.
- One of the planets in the opening is Zeenu from Planet Sheen. Otis and Pig also have cameos in the show's pilot.
- This is the only time Bessy helps with the adventure. She helps by milking Otis.
- This is one of the only episodes where we see Otis being milked.