- This page is for Summerween, the episode. For the holiday, see Summerween (event).
It's Gravity Falls' version of Halloween that takes place in Summer with Jack-o'-melons and lots of trick-or-treating. Dipper and Mabel are excited to join in on the fun, but when Wendy casually mentions that trick-or-treating is for kids, Dipper’s whole outlook on the evening changes. The night gets even more complicated when a monster that Dipper accidentally insulted makes them fulfill his candy quota by the night’s end or else he will eat them.
Dipper, Mabel, Soos, and Grunkle Stan drive to the Summerween Superstore to prepare for Summerween. Stan explains that the locals wanted to celebrate Halloween twice a year, so they created Summerween, a Halloween in the middle of the summer. Soos finds funny cackling skulls in the store and he keeps pressing them, much to his amusement. Mabel and Dipper are trashing the store costumes riding a wheelbarrow while Grunkle Stan gets some material for scaring trick-or-treaters. The cashier calls security due to the disturbance they're making, so Grunkle Stan throws a smoke bomb at the cashier and runs away with the gang, paying for the things with "Stan Bucks," Stan's poorly drawn counterfeit money.
Dipper and Mabel are planning out Summerween when Soos tells Dipper and Mabel about the Summerween Trickster. If the children do not have Summerween spirit, the Summerween Trickster eats them alive. However, Dipper begins throwing out candy that he deems as trashy "loser candy" that Stan had bought to hand out, unaware that someone is watching him from afar.
The doorbell rings and Dipper goes to answer it. Dipper is surprised to find Wendy and Robbie at the door. When Robbie asks Dipper if he is going trick or treating, Wendy tells him that Dipper isn't because trick or treating is for kids. Dipper reluctantly agrees with her. Wendy invites Dipper to Tambry's Summerween party, and Dipper says he will go. However, Mabel has invited Grenda and Candy to go trick or treating. Dipper fakes being sick so he can go to Tambry's party. However, the doorbell rings again, and this time, it's the Summerween Trickster. Dipper mistakes him for a normal trick-or-treater, says he is too old for trick-or-treating, and slams the door on him. The Trickster knocks on the door again, but Dipper slams it in his face, angering the Trickster. Mabel scolds Dipper and opens the door again. The Summerween Trickster now breaks into the Mystery Shack and tells him, Mabel, Grenda, and Candy that if they don't deliver 500 pieces of candy to him by the time all the jack-o'-melons in town go out, he'll eat them, proving that he will keep his promise by eating a random trick-or-treater named Gorney who arrives at the shack.
They head over to Lazy Susan's house to trick-or-treat. Because Dipper refused to get dressed up, they only get one piece of candy each, and he receives none. Because of this, Mabel decides to dress Dipper up and act cute whenever they go to houses, which greatly increases their candy yield. Eventually, they end up with 499 candy pieces, and Mabel decides to go get the last piece with everyone but Dipper while Soos goes and gets his truck so they can deliver the candy. Unfortunately, Wendy and Robbie arrive in their van and Dipper takes off his Summerween costume and pushes the supply of candy behind a bush.
When Dipper says he will be at the party soon, Wendy and Robbie take off in his van and Mabel discovers why he faked being sick earlier. It doesn't get any better; the candy has fallen off a cliff behind the bush and into a river because Dipper had not been paying attention, and everyone begins blowing out the candles in their jack-o'-melons. Dipper, Mabel, Grenda, and Candy manage to stop Old Man McGucket from blowing out his jack-o'-melon, but when they breathe a sigh of relief, the jack-o'-melon goes out. The Summerween Trickster then arrives.
Meanwhile, Grunkle Stan is having a difficult time trying to scare two kids. He even has Waddles burst out of his chest in an attempt to scare them, but the kids are not scared due to watching horror movies ever since they were two years old. The kids scare Grunkle Stan with a "screamer video," and Stan runs back in the Mystery Shack in disgrace.
Soon, the Summerween Trickster tries to eat Dipper and Mabel, but suddenly, Soos comes out of nowhere and drives his truck straight through the monster, smashing him to pieces. The kids get into the truck, but Mabel gives Dipper the cold shoulder for not wanting to trick-or-treat with her.
Unfortunately, the Summerween Trickster comes back to life as his pieces re-assemble, and he pursues the truck. Dipper, Mabel, Grenda, Candy, and Soos hide in the Summerween store, and Mabel reveals she was upset with Dipper because she was worried this will be the last time they'll trick or treat.
They are almost in the clear when Soos turns on a cackling skull that he was playing with earlier and the Summerween Trickster finds them. The Summerween Trickster is revealed to be an amalgamation of pieces of "loser candy" no one wanted and tossed in the dump. It eats Soos and then tries to eat Dipper and Mabel. However, Soos eats the monster from the inside out, and the Trickster collapses. The Summerween Trickster then confesses that all he wanted was someone to enjoy his candy, and he starts crying tears of candy corn as Soos happily eats him.
Grunkle Stan finally manages to scare the two kids after they sneak into his house and accidentally see him half-naked in his bathroom to "wash off the shame," and the kids drop their huge sacks of candy while running away. Dipper, Mabel, Soos, Grenda, and Candy finally get back to the Mystery Shack and find Wendy back early from the party. Dipper confesses to Wendy that he was trick or treating, but she replies that the party was lame because of Robbie ate a lollipop stick-first and had to go home early. In the end, everyone watches TV eating the candy Grunkle Stan got from the two kids. Grunkle Stan explains that Summerween isn't about candy or scaring others, but a night to celebrate pure evil. After some maniacal laughter, Soos confesses "I ate a man alive tonight," and everyone glances strangely at him.
- Directed by:
- With the Voice Talents of:
- Kristen Schaal as Mabel Pines
- Jason Ritter as Dipper Pines
- Alex Hirsch as Grunkle Stan and Soos Ramirez
- Jeff Bennett as Summerween Trickster
- T.J. Miller as Robbie Valentino
- Linda Cardellini as Wendy Corduroy
- Gregg Turkington as Toby Determined
- Carl Faruolo as Grenda
- Niki Yang as Candy Chiu
- Keith Ferguson as Deputy Durland
- Jennifer Coolidge as Lazy Susan
- Kevin Michael Richardson as Sheriff Blubs
- Grey DeLisle as Gorney
- Additional Voices:
- Casting by:
- Robbie and Wendy are still dating after starting their relationship in "The Time Traveler's Pig."
- Candy and Grenda continue their friendship with Mabel as started in "Double Dipper."
- The Explosion muffin that Robbie spray painted on the water tower, first seen in "The Inconveniencing", appears once again.
- The '90s teenagers that caused Ma and Pa's death in "The Inconveniencing" are shown again as contributing factors to the creation of the Summerween Trickster.
- Viewership: This episode was viewed by 3.478 million people on its premiere night.
- The Summerween Trickster can be seen among the pictures in the theme song, albeit with an apparent orange skin color.
- The Summerween Trickster is bright purple in the promo for this episode. 
- This episode takes place on Friday, June 22, 2012 as seen on Stan's calendar. It is notable that the summer solstice (Midsummer or St. John's Night/Day) falls on or around this day each year; in many European countries this day was associated with the same sort of witchery and tricks that modern Americans associate with Halloween (though due to changes in the calendar the day was formerly calculated on the 23rd/24th).
- After Soos bursts out of the Summerween Trickster, the piece of the Trickster that he is eating is heart-shaped.
- Candy's photo of the Trickster has the equivalent of the English term, "awesome" in Korean on it, according to Niki Yang. It's actually closer to "OMG" or "What the heck."
- This is the final episode to be aired in 2012 as no episodes aired in December.
- Among the LOLCats style photos, Waddle's pie chart only adds up to 98%.
- Two of the percentages are 6 and 18, right next to each other.
- The bottom of the poster for Tambry's party says: Not S+P approved. S+P refers to Standards and Practices, which is a joke Alex Hirsch used in exchange of a joke about spin-the-bottle that Standards and Practices did not approve. 
- In the cold open, Dipper and Mabel pass by a shelf of masks, which are actually the faces of crew who work on the show.
- The man with the baseball is John Aoshima, to his left is Erik Fountian, and Matt Braly.
- During the end credits, the cryptogram says "YILFTSG GL BLF YB SLNVDLIP: GSV XZMWB." Once translated it reads: "BROUGHT TO YOU BY HOMEWORK: THE CANDY." Homework: the Candy is one of the brands of candy in the Mystery Shack's bowl of "loser candy."
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