It appears in "The Inconveniencing". Mabel thought that the candy was banned in the United States; however, the Dusk 2 Dawn still carried it. After eating "bleven-teen" packages of Smile Dip, Mabel began to hallucinate. Among her hallucinations were the Flavor Pups, the Smile Dip mascots, where one of them offered her to eat his candy paw, which was a mirage. The second time, she sat on an Aqua Colored Dolphin with muscles, horn honks, and four arms that constantly hurled out endless rainbow trails. At the end of the episode, Mabel says Smile Dip is "evil" and she will never eat or do anything again.
There is an allusion to Smile Dip in "Boyz Crazy". When Mabel and her friends start to dance in celebration of Sev'ral Timez coming to town, Dipper asks if she had gotten into the Smile Dip again.