Peggy McGee (also known as The Pyramid) is the main antagonist of the Phineas and Ferb episode, Thanks But No Thanks. She is the former neighbor of the Flynn-Fletcher family who was known to be a notorious con artist.
She was voiced by Goldie Hawn.
Peggy first appeared at her window as she witnessed Candace Flynn fuming her failures to expose her brothers' antics to their mother Linda (notably on their latest project with human pyramids to make sports more fun). Eventually, Peggy calls out to Candace and admits that she saw the boys' previous adventures and inventions and is very astounded by them. Sensing an opportunity, Candace decides to have Peggy come over to the Flynn-Fletcher house and explain everything to Linda, but Peggy is too scared to leave her house. Candace then settles in bringing Linda over to Peggy's house.
However, every time Candace brings Linda over to the backyard to see Peggy, the latter is nowhere to be seen, and an annoyed Linda leaves right before Peggy returns to the scene, much to Candace's frustration. However, in the end, Candace finally got Linda to see Peggy in person at the front door, only to find out that Peggy is being arrested by several police officers. Linda and Candace are confused by this turn of events until one of the officers exclaimed a horrible truth: Peggy is being arrested for fraud as she was behind a "pyramid scheme" selling perspective-painted flat triangles as pyramids around Danville for profit. The officers also found a stash of her triangles inside her house as evidence of their findings.
Peggy is then sent away on a police car to face trial for her crime, but not before she vows to return back to the neighborhood before Linda serves pie for her family. Realizing now that Linda will never believe of what Peggy would say to her (due to Linda's disgust over the pyramid scheme), a disappointed Candace finally gives up in busting her brothers for the day.