At first, she thinks it's the curry. She doesn't normally eat hot food (like, ever. Even if the curry wasn't even that hot), so the rumbling in her tummy seems normal. Almost like indigestion without the burning sensation.
And then, a thump.
Anna's talking about school, ranting about something or other when Elsa plucks her hands from their midair dance and presses them against her stomach.
"Elsa, what are you...doing..." She trails off when she feels it, and her eyes seek Elsa's. "Oh my god," she says. Elsa nods, her hands covering Anna's.