Waddles' first appearance is with Mabel in the opening credits, in which Mabel is hugging him.His official debut is in "The Time Traveler's Pig," where Mabel wins him in a "Guess the Critter's Weight" game run by a carny. She looks at the pigs until one of them oinks, which she interprets as him saying either "Mabel" or "Doorbell." Taking this as a sign, Mabel asks the carny to let her guess the pig's weight. He tells her his name, "15-Poundie," giving her the answer to his weight. As the pig's name is "15-Poundie," Mabel guesses correctly that he weighs 15 pounds. The carny accuses Mabel of being a witch after giving her the pig. She takes the pig, renames him Waddles, and quickly forms a great friendship with him.
The bond between Mabel and Waddles is strengthened each time the twins travel through time, as she and the pig do things such as sharing pizza and taking photographs at photo booths. As a result, she spirals into depression when she loses him to Pacifica Northwest in the only successful Dipper timeline. After realizing how much Waddles means to her, Dipper goes back in time and sacrifices his chance with Wendy, allowing Mabel to re-win Waddles. To show her appreciation, Mabel sends Waddles to retrieve the caramel apple Robbie is sharing with his new girlfriend, Wendy. This startles Robbie, causing him to drop the apple and knock over a barrel of hot water, painfully shrinking his pants.
In "Fight Fighters," Waddles sits next to Mabel as she plays a card game with Grunkle Stan and before the fight asks if they want her to sic Waddles on Robbie again, referring to "The Time Traveler's Pig". He is also there when Mabel watches Grunkle Stan watch TV. At another point he sits next to Mabel at the table while Dipper worriedly paces about his upcoming fight with Robbie.
Grunkle Stan later uses Waddles in attempting to scare off two kids, and makes it look like Waddles is coming out of his stomach. At the end of the episode, Waddles eats some of the candy Stan received while everyone watches a horror movie for the remainder of the night.
Grenda, Candy, and Mabel are later seen taking pictures of Waddles and adding captions, similar to internet memes such as the "lolcat."
In "Boss Mabel," Waddles is first seen watching Cash Wheel with Dipper, Mabel, and Grunkle Stan while eating Chipackerz. When Mabel becomes the boss of the Mystery Shack, she makes Waddles her secretary. Near the end of the episode, Mabel asks Waddles for his opinion on Stan's apology song. Waddles reets, and Mabel declares take thirty.
In "Bottomless Pit!," Waddles is first seen in Dipper's story, "Voice Over." Mabel, Wendy and Soos play a variant of spin the bottle called "Spin the Pig", in which they spin Waddles and whomever he lands on must kiss him. He is later seen in Mabel's story, "Trooth Ache," when Mabel asks Waddles for advice, and then pretends like Waddles is answering.
In "Carpet Diem," Waddles is shown squirming on the carpet and when Soos pats his head, they switch bodies. When this happens, Soos leaves the Mystery Shack on an "adventure" while Waddles walks around the Mystery Shack looking for things to eat. Eventually Waddles ends up in the gift shop, and starts chewing on some clothes. When Wendy walks in and sees Waddles (whom she mistakes as Soos obviously since Waddles is in Soos' body) she leaves, and next Grunkle Stan walks in. After explaining that Stan needs to cut Soos' pay, Waddles puts his hand on Stan's nose and starts disturbing him. Eventually Stan gives in, and gives Soos a raise instead. Soon, A woman walks into the shack and asks for directions. Waddles (in Soos' body) sees the door open and walks through. The woman thinks he is showing her the way, and follows him. Later in the episode, Soos and Waddles get back into their own bodies.
Waddles is seen briefly in "Boyz Crazy," when he is sitting by Candy while the girls are getting ready to go to the Sev'ral Timez concert. He then is hugged by Dipper when he hears Wendy almost breaking up with Robbie. He is again seen when Deep Chris pets him on the head and says, "What up, girl?"
In "Dreamscaperers," Waddles is briefly shown in the beginning of the episode. He is laying down behind to Mabel, sleeping, as Mabel and Dipper play Conflict Boat. Then, when Grunkle Stan calls down the Pines twins, Waddles perks up, but doesn't leave with the twins.In "Gideon Rises," Waddles first appears in the Mystery Shack's Grand Closing, where Gideon Gleeful, who had taken possession of Waddles, presented him to his audience as Li'l Gideon Jr., Gideon Land's mascot. Later, when Li'l Gideon is looking through Journal 2, Waddles tries to escape through a window, but Gideon uses a whistle to force Waddles back into a corner of the room, leaving Waddles cowering. Later, after Gideon is proven as a fake and is arrested, Mabel is seen holding Waddles in the air as his Li'l Gideon Jr. costume burns in the fireplace nearby.
Waddles is a light pink pig with a darker pink spot on his left eye and two spots on his left side, close to his tail. His snout is a slightly darker pink, he has a short, quite curly tail, his hooves are greyish black, and he has a rather plump face. Waddles weighs 15 pounds, and his favorite food is caramel apples. On Summerween, Waddles wore a costume that was made to look like a business suit, a brown coat, a dark brown collar, a white shirt with a red tie, and black shoes.
- Intro: "Gravity Falls Main Title Theme"
- 109. "The Time Traveler's Pig"
- 110. "Fight Fighters"
- 112. "Summerween"
- 113. "Boss Mabel"
- 114. "Bottomless Pit!"
- 115. "The Deep End"
- 116. "Carpet Diem"
- 117. "Boyz Crazy"
- 118. "Land Before Swine"
- 119. "Dreamscaperers" (no lines)
- 120. "Gideon Rises"
- 7. "Mabel's Guide to Dating"
- 8. "Mabel's Guide to Stickers"
- 9. "Mabel's Guide to Fashion"
- 11. "Mabel's Guide to Art"
- Waddles was named by Aury Wallington, one of the writers for the show. She named him after her own pet pigs she owned during her childhood. Every year she'd raise, care, and love the pig for months, and every year her family would cook and eat Waddles. She'd get another pig for 4H and the cycle repeated itself for years.
- Alex Hirsch gave Mabel a pig because his sister, Ariel Hirsch, always dreamed of having one and has a pig shrine in her room.
- Waddles was nominated for Favorite Animated Animal Sidekick at the 2014 Kids' Choice Awards.
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