Ma & Pa Duskerton are the main villains in Gravity Falls episode, The Inconveniencing. They were once the owners and attendants of the now abandoned Dusk 2 Dawn convenience store and now haunt it to prevent teenagers from breaking in.
When alive, they had to deal with obnoxious teenagers that liked to wreck havoc in the store so they had to ban all teenagers permanently. In return, they boomed their "new-fangled rap music" out loud, the hateful and shocking lyrics of the songs caused the couple to have a heart attack and die simultaneously.
When Dipper, Mabel joined Wendy's teenage friends went to the abandoned store to have fun, Dipper began to notice several paranormal happenings. He became alarmed and told the group that they should better leave, which resulted in they becoming mad at him and beginning to think he had faked his age, which he did. Even Wendy whom Dipper had a love affection, was beginning to doubt him so he decided to try a dare of laying down in a corpse silhouette in the store to regain respect. This, however, caused the ghosts to manifest to all in form of strange phenomena such as the store turning upside down and the teenagers being uncannily captured one by one and imprisoned into several parts of the store. Also, he possessed Mabel.
Dipper saw that all of those who were captured exhibited traits of normal teenagers so he decided to confront them by revealing his real age in front of Wendy ("I AM NOT A TEENAGER!"), they manifested in the form of translucent two old selves and calmed down. They told him that they are willing to set his friends free if they promise to go and see something that defines him being a kid, hesitantly, he does the "Lamby Lamby Dance" he used to do as a toddler and Ma and Pa both disappear, setting their friends free.