I love the scene in Twinkle Wish Adventure when Scootaloo and Sweetie Belle are doing a terrible job of protecting Twinkle Wish's box, right after the song Somewhere Super New.
This will not do it justice, but here's a transcript of my favorite exchange in the movie:
Spoiler
Sweetie Belle: Want a cookie? I made them myself! They're yummy oatmeal-raisin-apple-caramel-walnut-upside-down surprises!
Scootaloo: Uh, no thanks, Sweetie Belle...
Sweetie Belle: Okay.
(pause)
Sweetie Belle: Can I have a cookie?
Scootaloo: Sure.
Mayor Flitter Flutter: (approaches) Hello, hello, hello! Where's Cheerilee?
Sweetie Belle: Uh, she's gone... ballooning?
Mayor: WHAT?
Scoots: She... means.. sh-she's.. gone to... GET balloons... for... for......
Mayor: The festival? She's getting decorations for the festival?
Sweetie: If you say so!
Scoots: So, we're watching the box for her.
Sweetie: We didn't open it and let a crazy old dragon steal the wishing star or anything!
(pause)
Sweetie: Want a cookie?
Mayor: On, no, thank you! I'm watching my figure.
Scoots: Watching it... do what?
(pause)
Mayor: Hmph. (leaves)
Sweetie: Hm, that went well! (eats cookie)
This scene is seriously the best part of the movie. Sweetie Belle is just so cheerful and completely unfazed by anything, while the mayor actually buys their clearly poorly-thought-out lies (which some may find annoying, but she does catch on later in a more serious scene). The pauses make it just perfect! I recommend you watch it if you haven't seen it, if only for this scene!
There may be some "deeper" quotes out there, but this is just what came to my mind!