Bubbie is a large blue sperm whale. Although they are not usually visible, she wears glasses. The inside of her body serves as a house for Flapjack and Captain K'nuckles, even containing a bathroom for them to use. While Flapjack and K'nuckles are inside her mouth, Bubbie takes care not to move her tongue and even has the ability to speak through her blowhole.
Bubbie is very sassy and can be extremely overprotective when it involves Flapjack's safety. She dislikes K'nuckles' influence on Flapjack, as it always leads to trouble, and all Bubbie wants is for Flapjack to remain the sweet angel he really is. Regardless of K'nuckles' obnoxious attitude towards her and Flapjack, she cares about him like family. In one episode she even admitted that she was proud of K'nuckles for attempting to lose weight.
Bubbie dislikes bragging, as she believes that it can only cause havoc in life. She has always dreamed of flying and sometimes wishes she was a bird. At times, Bubbie can feel lonely due to Flapjack and K'nuckles' adventures, so she goes into Stormalong to peep on its citizens and find out their secrets in order to pass time.
Bubbie was originally planned to be a whale-shaped submarine, however, the idea was later used for Whoosh.
Bubbie has a bell collection.
When the scene changes to the inside of Bubbie's mouth, her tongue never moves while talking; only her uvula does.
In the episode "Bubbie's Tummy Ache," it is shown that Bubbie is able to survive on land and even walk, as she entered a pie eating contest and was standing upright. However, in "Low Tidings" and "Oh You Animal!," she stated that land is dangerous for whales, likely referring that whales dry out on land.
Bubbie's name is heavily influenced by the Yiddish language, either coming from "Bubula," a Yiddish word for "baby," which is what she calls Flapjack, or "Bubbe," a Yiddish word for grandmother, pronounced the same way her own name is pronounced.
She is extremely ticklish.
In "Oh Brother!," it is shown that she discovered an infant Flapjack wrapped in seaweed, and because of his extreme angelic cuteness, she adopted him.