He has light blue skin as well as a pair of green trunks, a red and white party hat, and turquoise eyelids.
Role in series
Billy is first seen having a birthday party with his friends. Mr. Krabs is providing the catering services at his party. When they are playing with the piñata, Billy smashes 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 threatens Mr. Krabs that if he does not get him his cake, he will set off the fireworks but Mr. Krabs reprimands him for this because it is too dangerous for children to play with fireworks.
Billy realizes his actions by stating nobody ever cared enough to explain and affectionately calls him his father before hugging him. However, Mr. Krabs throws Billy down the laundry chute when he hears Ms. Mildred calling.
Billy eventually ends up in Ms. Mildred's bedroom and starts jumping on her water bed. When Mr. Krabs sees this, he tries to stop him. However, Mr. Krabs' feet puncture the holes on the water bed and cause the mansion to flood. Billy is last seen surfing on Mr. Krabs' check as he gets himself splattered with his birthday cake.