Twilight realizes she never taught Spike the concept of object permanence, but he says he's fine. He turns it around on her: how would she like having somepony teach her object permanence like a foal? She realizes that would be a wonderful experience, as she doesn't remember it back when she learned that since she was just a foal. She casts a spell to remove her own object permanence. Can you guess what happens next?

Author's note: Just a cute little fast-paced one-shot. Cake twins are referenced but not seen nor heard; they're too awful for me to even touch. 100% Spike's-the-hero bait.

Wikipedia entry on object permanence.