"Twilight, dear, stop it with the screaming! You'll scream your head off at this rate. What even is the matter, darling?"
An anticlimactic pop accompanied Twilight's head standing up, jumping off her neck, and skittering away, still screaming all the while.
Twilight's body continued to stand in place, an odd rumbling noise shuddering from within.
A loony, detached, toothy grin spread across Rarity's face as she accepted the new rules of reality and walked out the room.
As for Twilight's body, a new head had already been magically poofed into existence for nothing other than being a plot device. Taking a deep breath, Twilight opened her new mouth and--
Today was a long day for Ponyville following the invasion of Twilight headcrabs.