The Legend of Zelda: Majora's Mask/Toilet Paper!

Requirements

 * A paper item (i.e., Deed or Letter)
 * Room Key (Optional)

Rewards

 * Piece of Heart

What to do
Begin by going into the Bomber's Hideout and use the telescope to get the Moon's Tear, then trade the Pearl for the Land Title Deed. At 1:45 PM, enter the Stock Pot Inn and speak with Anju as Normal Link. She'll ask you if you have a reservation. Respond "Yes" and she'll look at her book. Apparently your name is in there! She gives you the Room Key, which allows you to enter the Stock Pot Inn after 8:00 PM.

Deku Link can also enter the inn from the second floor, using a nearby deku flower. When you fly onto the balcony, the door allows access to the inn (but not the rooms on the first or second days).

Enter the Inn on Midnight of any day and go to the toilet (Located underneath the stairs on the first floor). A hand will come out asking for paper. Hand over a deed (Or letter) and he'll use it for his... business. Afterwards, he'll throw a Piece of Heart out of the toilet.