Topsy is a minor protagonist in the film Mary Poppins Returns portrayed by Meryl Streep as the cousin of Mary Poppins, who seeks her out to fix a broken Banks family heirloom, but makes the mistake of visiting Topsy’s shop on the second Wednesday of the month, when gravity-challenged Topsy’s life flips upside down.
When a fight over their late mother's Royal Doulton Bowl accidentally leaves a crack in the family heirloom, Mary Poppins takes the Banks children into town to have it repaired by "her cousin." With Jack along for the trip, they wind up on a street that looks like an offshoot of Diagon Alley. At the end of the street, they find a tiny little door and a long name starting with "Topsy." This is how Mary addresses her too, "Cousin Topsy," a woman who can fix anything.
Topsy's song and (upside down) dance number is called Turning Turtle, comparing herself to a turtle who has been flipped onto its back and is unable to function until someone comes along and rescues it. This being the world of Mary, she is having none of it. Her advice to Topsy is if life insists on turning everything upside down, she should stand on her head and be upside down with it. The change of perspective should solve everything.
Unsurprisingly, Mary is correct in her assessment as the entire group stands around on their heads discussing how much better the world looks from this angle. With Topsy's life righted for the moment she agrees to fix the family heirloom, to the great relief of the Banks children. Also apparently her house approves too because as the group leaves it turns itself back over, allowing her to work until the next second Wednesday rolls around.