1) After you've obtained Farore's Pearl go to Outset Island with a Fairy in a bottle.
2) Stand in front of Grandma with the Fairy equipped to a button.
3) Press the button to use the Fairy and then immediately press start(you more or less have to press them at the same time, otherwise the game won't pause).
3) Equip any item other than a bottle to the button that the Fairy was on and unpause.
The Fairy will heal Grandma, and she'll say her part about her being a terrible Grandma, then the game crashes.