Martha "Dumptruck" Dunnstock, portrayed by Carrie Lynn, is a minor character of the cult classic film Heathers, and a secondary character in the musical. Martha is relentlessly teased throughout the film. The first time Martha is shown, Heather Chandler forces Veronica Sawyer to forge a love note under Kurt's name. When Martha brings the note to Kurt, he laughs in her face and she storms out of the cafeteria.
Not much is said about Martha's early life other than being shown that she was childhood friends with Heather Duke.
Martha Dunnstock and Heather Duke were close friends during their childhood. It isn't explained why the friendship ceased, but it is made clear that Heather Duke does not want anyone at Westerburg High to know about their past friendship.
At the end of the film, free at last of the Heathers' toxic influence, Veronica Sawyer invites Martha Dunnstock to hang out on prom night and watch movies with her. This is the start of their friendship.
Martha is seen sitting in the gym after the murders of Heather Chandler, Kurt, and Ram. At first, it appears she is attending a sporting event but is really alone. She spills a drink on herself and then the scene flashes to Martha walking into traffic with a suicide note pinned to the front of her shirt. Luckily, she survives but is badly injured and ends up being wheelchair bound. Heather Duke continues to mock her for trying to "act popular" by committing suicide like Heather, Kurt, and Ram did.