This is something

Horrifying

The door was shut.

That usually meant he wasn't supposed to go in.

Alas however, in grave times risks must be taken.

Sidney Pines opened the door to his father's study. It was dimly lit, and the walls were lined with shelves of books and specimens of plants and creatures you could never hope to find in your garden-variety zoo book. There were things both wondrous and horrifying lurking along these walls and he knew it.

But, nothing could have prepared him for what he saw upon entering the room. A sight more horrifying that anything found on his father's shelves.

His mother and father on his father's desk, kissing fervently. They'd stopped when they saw him, but he'd already seen more than enough to be scarred for life.

Old people love. Ewwwww.

"H-hey Sid. Need something?" His father said, tentative giggles escaping from both his parents as they untangled from each other.

He would've asked to have the last 10 seconds of his life wiped from memory, but he had a mission.

"We're out of milk." He said.

Dipper just stood there, blushing, and his eye twitched. This kid. "Yeah, uh, okay. Look, your mom and I are in the middle of something."

"Yea I can see that."

Dipper's blush deepened.

"Sidney." His mother chimed in. "There's that grocery store not far from here. You can take some money from my purse, ride your bike up and get some milk, okay"

Sidney made an expression that Dipper recognized 'works for me.'

"Thanks mom. And, uh, enjoy yourselves or whatever."

And with that, the 12 year old left.

Dipper eyed the spot where his son was just standing, before turning back to his wife. "That kid. He gets that from you, you know." He said, eyeing her expression.

"What?" she asked, still trying to contain her laughter.

"That attitude. 'we're out of milk.' Can you believe the way he talks?"

"Oh please. He doesn't like being talked down too by adults, and wants to seem mature. Who, pre tell, does that sound like?"

Dipper sighed. "Okay, fair enough." He said. "Sure it's a good idea letting him off alone like that?"

"He wants us to think he's responsible. This is a chance for him to show that he is. There's only like twenty bucks in my purse anyway." Pacifica replied.

She then grabbed her husband by the shirt collar. "Besides, we are now free to pick up where we left off, aren't we?"

Dipper smiled dreamily. "Incorrigible as ever." He said before the ravishing recommenced.