(Why am I doing this?)

(okay, I'm done now.)

Look closely at the dialogue bubbles in Panel 5. If you draw your attention to the center of both bubbles where they meet, you'll notice one interesting feature.They aren't two separated bubbles! Albeit they are two different colors, however the bubbles themselves are fused! Ergo, one may deduct that it is to bedialogue bubble, thus both dialogues being said in unison! If you also look at their faces, Pinkie Pie's expression almost mirrors that of Twilight Sparkle's. This could very well be because she predicted not only what Twilight was going to say, but also in what fashion! In other words, Pinkie Pie didn'tTwilight Sparkle, per se... rather, sheher!