Dipper drag Mabel to Wendy's Kitchen. Where he have to tell her what his sister dare him to tell him.
Dipper: okay I gonna tell you what happen. But you have to promise me you won't tell anyone. If you do me and Wendy will be in so much trouble.
Mabel: oh my gosh Dipper. You didn't do what I think you did. Did you.
Dipper: yes. I had sex with Wendy while we were in the attic.
Mabel: oh that. That's a relieved. I thought you and Wendy smoke something funny. Don't worry Dipper I'll keep you secret.
Dipper: thanks Mabel.
Then they Went back to the living room. But Everyone is leaving.
Dipper: hey where everyone going.
Nate: oh we gonna catch a movie.
Wendy: I have to stay here. But you and me and Mabel will keep having fun.
Tambry: ohh I feel so sick I have to lay in my bed for a month.
Wendy: see you guys later.
Then all of Wendy friends left.
Dipper: so what now.
Wendy: check this out.
She reveal a secret department in the walls next to her living room T.V
Wendy: My dad's collection of pg-13 an r rated movies. We can watch them all night.
Hours later. Wendy and the pine twins watch so many movies. Until. Mabel started to fell asleep. But Dipper is still awake and so is Wendy.
Wendy: hey while your Sister asleep. You and me have a second round.
Dipper: okay.
Then Dipper and Wendy sneak to her room. Got on her bed. And they started to make out lightly. Wendy grab Dipper's hand and make it squeeze her breasts. Dipper blushes brightly. Then Wendy took off her pajamas. Just revealing her bra and underwear. Dipper Blushes even Brighter. Then Dipper took off his shirt. Then his pants. Then Wendy took off the remaining clothing she had. Then Dipper took off his underwear. Then he stick his manhood into Wendy's womanhood. They feel so much pleasure. Even more a second time. They keep feeling good for 12 minutes. Then they both came. And Collapse in pleasure.
Wendy: whoa that's more intense then last time.
Dipper: wait your not getting pregnant are you.
Wendy: no I taking birth control. If I get pregnant now. My dad will chase both you and me with and ax.
Dipper: will I hope he never knows.
Wendy: love you.
Dipper: love you too.