- Name: Bertha
- Profile: Skinniest girl at Miss Shannon's
- Status: Knobby-kneed
- Catchphrase(s): "Gross!"
- Identified by: Stacks of Heartthrob Magazines; bags of snack foods
Bertha is a tall girl with buck teeth. Based on how she reacts to Betty, she seems to have a high tolerance to gross things.
Beetlejuice (especially as Betty) calls Bertha "Burp" (name-games aside, he's probably making fun of her mouth shape.)
In "Laugh of the Party", Bertha's Halloween costume was a tall, yellow chicken... might've been mistaken for a reference to the rubber chicken gag (via Claire's mistreatment upon arrival), if she didn't arrive at Lydia's party with an egg in her "wing".
While camping in the Neitherwoods, she and Prudence took on a Tarzan persona, complete with vine-swinging and the yell.
In an alternate reality in which Beetlejuice never met Lydia (or Prudence), Bertha was making wisecracks about how "uncool" Lydia is next to Claire, and even tries to copy Claire Brewster's valley girl accent. Apparently, she associates strongly with people who have confidence (something Lydia would lack if not for BJ's shenanigans).