Wonka invents a gum that contains an entire three-course dinner: tomato soup, roast beef with baked potato and blueberry pie (pea soup, roast beef and blueberry ice cream in the theatrical shows), but forbids Violet to chew it as it is not ready for human consumption just yet. Violet rudely snaps that she holds the world record in chewing gum and begins going at it anyway, ignoring Wonka's protests. However, the blueberry pie stage is defective, which causes Violet to turn blue and expand into a giant blueberry. She is unable to walk due to her girth, and Wonka tells the Oompa Loompas to roll her to the juicing room to extract the blueberry juice immediately, implying that more swelling will cause her to explode.

In the original, Violet blows up to smaller proportions but everyone (including her father) is still surprised; she was seen wearing a red buckled belt, but it pops off as her body becomes too big for it. She can waddle, but very slowly due to her girth, and before she can waddle too far, she is lowered to the ground by the watchful Oompa-Loompas. She is rolled to the juicing room by a team of Oompa-Loompas but is not seen again, and there is a twist as Mr. Wonka said she might explode. Violet is not seen again after being rolled away, but Wonka simply assures Charlie that all the other children will be returned to their normal "terrible" selves. She is also the only one present during her song in the 1971 film.

In the 2005 version, Violet grows more than just a few centimeters, instead swelling to a much higher rate than the novel, almost reaching the Inventing Room's catwalks. Her mother does not seem to care about this predicament happening to Violet herself, but that her daughter can no longer compete, and asks Wonka about the subject. Veruca responds, "You could put her in a county fair," and by the look on her face, Scarlett is both offended and considering the idea. She is also seen exiting the factory with her mother after the tour. She has been deflated back to normal size, but rather than just walking, she somersaults, cartwheels and backflips down the stairs and the front walk, apparently becoming more flexible (like chewing gum, appropriately) and her skin, hair and clothes are now a seemingly-permanent shade of blue. She is actually pleased with her new pliability, but her mother is very angry with her daughter for disobeying Wonka's orders and turning blue (despite Scarlett encouraging her to do so [disobey his orders] herself), and judging by the look on her face and the tone of her voice in her final line ("Yes, but you're blue."), she is fed up with coaching her daughter and treating her like an overconfident athlete, her exceeding pride in her entirely gone. In the novel, Violet ends up with purple skin but there is no mention of increased dexterity.

The filmmakers of the 1971 adaptation simulated the blueberry scene by inflating Nickerson in a rubber suit and composed her outline in two halves of a styrofoam ball, and it took 45 minutes to get her into costume. Nickerson was unable to go to lunch during rehearsals; instead she was rolled around on set every five minutes to keep blood circulating. Nickerson recalls that Julie Dawn Cole, who played Veruca, saw her as the "cool American girl", but "when she saw [Nickerson] as a big purple ball, [Nickerson] was completely embarassed." In the 2005 version, at the request of director Tim Burton, the filmmakers combined real footage of Robb with digital effects in order to increase the overall size of the blueberry rather than just the width (as depicted in the novel), as well as for the scene of Violet and her mother leaving the factory.