PROLOGUE
"Mabel, look at this!" Dipper shouted, shining a flashlight on the bottom of the house.
"Electric toothbrushes." Mabel said.
"SpongeBob ones as well. Why do any kids even like that show? I'd understand Mickey Mouse or Frozen, but SpongeBob?" Dipper annoyedly added.
They used the shovel they dug the hole they were in with to pull off the electric toothbrushes, which were superglued to the house.
The two climbed up out of the hole they'd dug underneath their client's house, and covered it up with the mountain of soil next to it. They knocked on her house's door, and told her the news:
"Good news. We found what was making your house vibrate. Someone was placing a bunch of electric toothbrushes underneath it and activating them. We successfully removed them." Dipper told the client.
"Excellent work! Here's your money. Oh, and, thank you. Truly."
She handed them the cash and closed the door.
"Woohoo! Another victory for the Pines Paranormal Protection Service!" Mabel victoriously declared.
"Yup. Back to HQ, Mabel.
Their HQ was a small building that used to be an old diner that went out of business when the twins were still kids. Their office was at the front, but they walled off a lot of the old dining space so they had room to live, like Stan. Outside they had put up big, bright letters that lit up at night which spelt out the company's name, with a massive Waddles sitting proudly on top. The twins went in and did the first thing they always do in their routine; check their emails (though Mabel always hugs Waddles first).
Lo and behold, they had a new email. Dipper, who managed to check it first as Mabel was busy hugging her favourite pig, mumbled out, "Dear Mabel and Dipper Pines, I have a problem in my home. We urge you to come soon. I am willing to PAY MORE due to the fact that I live in GRAVITY FALLS?!"
"WAIT, WHA-"
"Yours truly, PACIFICA NORTHWEST"
"WE-HE-HELL, LOOK WHERE WE'RE GOIN' THIS FINE SUMMER!" Mabel exclaimed in excitement.