Mailbox

 is the third animated short of Gravity Falls to air between Season 1 and Season 2. It premiered on October 15, 2013.

Overview
Dipper and Soos stumble upon a mailbox in the middle of the forest and make it their mission to discover who (or what) picks up the mail left inside.

Synopsis
The short takes place somewhere in the Gravity Falls forest. Dipper says he's going to investigate anomaly #54, a mysterious mailbox in the middle of the forest, with Soos coming along as Dipper's "team of experts". Soos places a piece of paper with "'SUP, DAWG?" written on it in the Mailbox and closes the lid. Seconds afterwards, the Mailbox begins to shake violently and the flag on the side magically moves. Dipper opens the Mailbox to see their letter has been replaced by a scroll that reads "HELLO DIPPER AND SOOS." Soos wonders if the Mailbox is all-knowing, and the duo decide to ask it more questions.

Soos decides to ask the Mailbox "WHAT DID I SHAVE INTO MY HEAD THIS MORNING?" and the Mailbox again answers correctly: A duckling with a paddle-ball. Soos thinks they should ask some more questions. Dipper decides to ask when the world will end (3012), while Soos decides to ask it what his dream woman looks like, to which the Mailbox gives him a drawing.

Finally, Dipper ponders what to ask the Mailbox, from when his death will be to the meaning of life, with Soos desperately trying to ask if aliens built the Pyramids, and what marshmallows are made of. Finally the duo agree: Learning who wrote Journal #3, one of Gravity Falls's greatest mysteries. However, Mabel arrives and puts a video of her sticking 100 gummy worms up her nose into the Mailbox, thinking it will be sent to her mom. It is replaced with a letter that reads "Your gummy worm video has disturbed and insulted me. You fools are unworthy of my great knowledge. The era of human enlightenment shall never come to pass." As Dipper finishes reading the letter, the Mailbox collapses in on itself and explodes. The short concludes with Mabel attempting to put more gummy worms up her nose and Dipper running to the camera.

Cast

 * Jason Ritter as Dipper Pines
 * Kristen Schaal as Mabel Pines
 * Alex Hirsch as Soos

Production notes

 * See also: List of allusions and List of goofs.

Character Revelations

 * Dipper is interested in the identity of who wrote the journals.
 * Mabel sticks gummy-worms up her nose.
 * Soos seems to be aware of 3.

Series continuity

 * Mabel wears her watermelon sweater from "Bottomless Pit!."​

Trivia

 * The wax stamp on the first letter is stamped with an infinity symbol.
 * In this short, Soos seems to have a lot more hair than he did in Little Dipper