Birch: C'mon Dipps, it's not the end of the world, you'll see. Things will work out.
Dipper: I guess?...Uncle Birch I wanna cookie?
Birch: Now Dipps, it's almost dinner time and your Mom told me not to let you have too many snacks.
Dipper: I wanna cookie?
Birch: You might spoil your appetite for dinner though Dipps?
Dipper: I wanna cookie?!
Birch: I told you, no.
Dipper: But they're right next to me!
Birch: No.
Dipper: I WANNA COOKIE!
Birch: 'sighs' OK, OK. But just one!
Dipper: 'happily munches on a cookie' YUMMMM!

In the chapter, though, the receptionist had already given permission.

But that scene is a little more amusing you gotta admit?

It reminds me of the Beach Bears' version of Christmas Don't Be Late.