Party Animals is the fifty-seventh episode in Series 2
While the Farmer is setting up his costume birthday party, Bitzer and some of the Flock play cards. But his horrible card skills send the cards everywhere. The Farmer then asks Bitzer to take the invitations to the postbox while he looks though costumes, and Shaun comes along. But Bitzer decides to use his horrible card skills to put the invitations in the mail. Shaun points to where the cards Bitzer actually threw them: the sewage! In shock, he dives into the sewage. When he comes up, he sees the invitations ruined. Both Shaun and Bitzer then have a vision that the Farmer is upset since no one came to the party. They both feel bad, but Shaun comes to Bitzer's aid. Bitzer then sneaks out the costume book. Looking for costumes that fit their satisfaction, they look for the right materials for the costumes. Day after day, the party is getting closer, and on the day of the party, the costumes are done. That evening, they arrive at the party in their costumes, such as a cow, a cowboy, a Dalek, a chicken, a monster, and even an actual sheep (that would be Shirley, who is too fat to fit in anything). After a while of partying, the costumed flock show the Farmer his present: a car (which is actually a cardboard cutout). When blowing out the candles on his cake, Shaun's cowboy bandanna flies off his face. The Farmer then almost realizes the costumed are the Flock, but Shirley then kisses the Farmer and makes him forget everything that just happened. The Flock cheer when the cowboy puts back on his bandanna. They then form a conga line, but one of Shirley's shoes fall off. They still do the conga all night. The scene then picks up the Farmer sleeping in the living room, trashed. After waking up, he realizes one of Shirley's shoes by the doorway, but sees Shirley wearing the same shoes. Solving the problem, Shirley soars the shoe into a bush, and the Farmer dismisses what happened. The episode ends with Shaun and Shirley laughing.
- One sheep is shown wearing a Dalek costume from the Doctor Who franchise.