One afternoon while Dipper was watching, someone knocked on the door. It was the mailman.
"A letter for Dipper Pines" he said.
"Thanks. " Dipper replied.

At the Northwest Mansion, while Pacifica was reading a book, the mailman knock on the door of her house. Then, she get the letter.

"For Pacifica Northwest"he said.

"Thank you." She replied.

When they both read it, it was an invitation from the princess of Arendelle. It says that they are invited. Actually, all the people of Gravity Falls are invited. When Dipper was done reading, Mabel went to the room.

"Hey bro, did you hear the news? There is a party and all of us are invited." She said.

"Yeah, but I'm not going." Dipper replied

"But, it's your chance to get a girlfriend." She pleaded.

"Fine, I will go." He said.

Then, they asked Grunkle Stan to buy them fancy clothes but he said he has no enough money.

Meanwhile, Pacifica went to her room and find some nice dress, but she wasn't able to find one since, it was all in the laundry. So she went to her favorite boutique.