He is a light olive fish with slightly light brown fins and lips. He wears blue jeans and a black belt with a silver belt buckle.
In his older appearances, he had his eyes on top of his and head, with bags under them.
He is seen as a student in Mrs. Puff's class. Later, he watches SpongeBob and Patrick fight but leaves after he notices SpongeBob and Patrick are punching, but missing at the same time to which he replies "This is embarrassing."
Squidward happily chats with him about SpongeBob not being there but Frankie gets annoyed with Squidward and asks for his change. When Squidward thought he gave Frankie change he actually gave him SpongeBob's socks and underwear.
He is seen trying to order when there is nobody at the boat due to Squidward "injury."
He is later seen when Mr. Krabs is giving Squidward a back massage and asks for a Krabby Patty during the process. An annoyed Mr. Krabs pulls money out of his pocket, goes into the kitchen to make a Krabby Patty, and brings it out all greased up and asks Mr. Krabs if he is going to wash his hands but first, but Mr. Krabs carelessly shoves the greasy Krabby Patty into Frankie Billy's mouth; Frankie Billy groans in pain as he holds his stomach.
He is seen in two different physical appearances; when he first arrives at the drive-thru, he is purple, and he orders a meal from the Krusty Krab, but because the window was small, SpongeBob has trouble getting the meal out of the window. He also tries to use a trampoline, but the meal falls on the customer, then he gives Mr. Krabs the bill to pay for his dry cleaning.
He is later seen again in his normal appearance, where, alongside two other fish, is angry when SpongeBob tries to give them the meal.
He tries to order a Krabby Patty and drink. However, Squidward, who is acting like a baby due to a head injury, makes baby noises, hits his head with a rattle, drools, laughs, and sucks on Billy's hand. SpongeBob peaks his head out of the kitchen windows and tells Squidward that Billy's head is not for eating. SpongeBob then takes a napkin and polishes Billy's hand. Squidward then sucks on Billy's hand. SpongeBob tells Squidward that his hand is not for eating either.
He is seen putting ketchup on his Krabby Patty. He, unknowingly, had an urchin on his Patty but the urchin gets away before he takes a bite. He later overhears SpongeBob talk about the urchin and flees the restaurant.
When Larry opens his gym, he said "You're the lobster, Larry! The Alpha Lobster!" When he is driving by the Krusty Krab, the grill falls on his boat and explodes. Like Fred, he yells "My leg!" but he says he is okay. The grill then falls on him again and he says that he is slightly less okay.
He appears as a scythe salesman when SpongeBob is about to fly in the air show. Sandy gets mad and tells him to leave.