He has light blue skin as well as a pair of green trunks, a red and white party hat, and turquoise eyelids.
Billy is first seen having a birthday party with his friends. Mr. Krabs was providing the catering services at his party. When they were playing with the piñata, Billy smashed Mr. Krabs' pants to get money and causes the other kids to chase him.
Throughout the episode, he keeps appearing in Mr. Krabs' shirt shouting, "I want my birthday cake!," to him causing the latter to throw him away only for him to return each time. After many attempts, he threatened Mr. Krabs that if he doesn't get him his cake, he'll set off the fireworks but Mr. Krabs reprimands him for this because it's too dangerous for children to play with fireworks. Billy realized his actions by stating nobody ever cared enough to explain and affectionately called him his father before hugging him. However, Mr. Krabs threw Billy down the laundry chute when he heard Ms. Mildred calling. Billy eventually ended up in Ms. Mildred's bedroom and started jumping on her water bed. When Mr. Krabs sees this, he tries to stop him. However, Mr. Krabs' feet punctured holes on the water bed and caused the mansion to flood. Billy was last seen surfing on Mr. Krabs' check as he gets himself splattered with his birthday cake.