[Muttering? Oh, you bet he's muttering and it's far louder than he would have wanted it to be. If Piper's listening, which she clearly is, she'll be able to hear him talking fairly animatedly about the dagger in her hands: What is it? What does it mean? Where did she get it from? Did it have something to do with Gravity Falls?

The shriek that comes out of him when his "secret" hiding spot has been revealed sounds as manly as puppy who just got stepped on. If it wasn't obvious that he was young before, it definitely is now.

Dipper closes the journal with a loud slam and, for reasons he doesn't quite understand, slowly starts to make his way out of the bush. He laughs nervously as he struggles through the branches.]

Sorry, sorry, I was just, uh ... I was just, you know, doing some bird watching. I wasn't trying to hide from you or your weird dagger or anything like that.

[Smooth.]