After barging in on Shining Armor peeing inside of Cadance, Twilight wants to know why peeing in somepony means love. Twilight takes her parents' advice of discussing it with Celestia, whom they say will give Twilight a much better and informative lesson. She shows up at Canterlot palace and asks Celestia to explain why peeing in somepony means love. Celestia teaches her all she needs to know, and the she gives a demonstration.
One night, Twilight makes a shocking discovery about the so-called "ghosts" that haunt her brother's room.
Twilight wants to find out why peeing in somepony means love, so she asks Celestia...