They both wake up screaming

Dipper: You guys ok?
Wolf: We just had a bad dream.
Dipper: You both had the same dream?

Rosie: Yeah, There was a weird Floating tri...

*Wolf pinches Rosie really hard on the arm*

Wolf: Time baby.
Rosie:It was a..
Wolf stares at Rosie in way that tells her that they shouldn't know... yet...
Rosie:...tiger head.
Mabel: That's kind of weird.
Dipper: Well grunkle stan can't know about you, so you guys want us to bring you any food or anything?
Wolf: I don't really care.
Rosie:Me neither.
Dipper: Ok see you guys in a bit.

After Mabel Dipper leaves Wolf then explains to Rosie about all of Gravity Falls episodes and shorts.

Rosie:So their Gunkle Ford is the Author?