She is referred to as "Lady Upturn the 333rd" in "Moving Bubble Bass."
She has light pink skin, dark yellow hair, lavender eyelids, and dark pink lips. She wears a dark blue dress with a light blue boa, a golden bracelet, and often holds a green purse with a small gold clamshell on it (a purple purse in "Gary's Got Legs"). She also wears blue high heels with light blue stripes, though in "Moving Bubble Bass" and "The Ballad of Filthy Muck" she wears blue high heels that are more realistic in design.
Unlike most fish, she has fingers and toes.
Role in series
After SpongeBob, Patrick, Squidward, and Mr. Krabs retreat from the children's birthday party they catered, they see Ms. Mildred looking at their truck, and she asks them if they are the caterers for her party. Mr. Krabs lies and says they are, and she pays him $50,000 in advance for the services.
At the party, she warns Mr. Krabs about the food service going out of control, and she later becomes angry when a food fight breaks out, before being hit with food and joining the fight.
At the end of the episode, she (and two other kids) are seen bouncing on SpongeBob, who has transformed into a bouncing house.
"Moving Bubble Bass"
When SpongeBob and Patrick are moving Bubble Bass' luggage to his grandmother'shouse, they encounter Ms. Mildred exiting the Jewelry Store, and she refuses to move out of their way. When they lose control of Bubble Bass' luggage, Ms. Mildred walks on a run-over Patrick, leaving her shoe in his mouth. She is soon run over twice by the luggage, and Patrick walks on her, leaving her shoe in her mouth.
Later, when SpongeBob and Patrick are hanging from the remains of the bridge, Ms. Mildred walks on the bridge's rope towards the two, which (along with three babies) weighs the rope down to the ground. She whacks Patrick on the head with her shoe and walks off the rope, flinging SpongeBob, Patrick, and the luggage into the air.
When SpongeBob and Gary are walking around in the Snail Park, Gary flirts with Ms. Mildred's snail. When her snail responds, Ms. Mildred glares at her pet in annoyance.
"SpongeBob's Bad Habit"
She appears as one of the customers in the Krusty Krab, where she is hit in the face by fingernails spat by Nat Peterson, clamping her eyelids shut. When she opens her eyes, she holds up a mirror and realizes that she now has fingernail eyelashes. Her appearance causes the mirror to shatter, making her scream in horror.
She received a minor redesign from "Moving Bubble Bass" onwards, with her feet being more realistic in shape. However, in "SpongeBob's Bad Habit" she has her original design.
Her name is never mentioned in "Krusty Katering," but it is revealed on the check she gives to Mr. Krabs.
Her bracelet often changes wrists between scenes, and one scene in "Krusty Katering" and "Gary's Got Legs" featured her wearing bracelets on both wrists.