Fairy adult

Start a new game and beat the Great Deku Tree dungeon to get the Kokiri Emerald.Instead of Exiting the forest via the main entrance/exit, the one guarded by the long haired Kokiri, go into the Lost Woods and through the tunnel warp to Goron city.Use the CC trick to get through the rocks blocking the tunnel.Beat the two other child dungeons without getting the Fairy Ocarina, wherever you need to use the Ocarina just use the Ocarina items glitch instead.Go to the Hyrule Castle drawbridge and watch the movie showing Zelda and Impa escaping.Get the Ocarina of Time from the moat and learn the Song of Time.Go into Kokiri Forest and then exit via the main entrance/exit, the cinema showing Saria giving Link the Fairy Ocarina will play, you'll get the Fairy Ocarina which will replace the Ocarina of Time, go forward in time and there you have it, adult Link with the Fairy Ocarina.
OR:
Do not go and get the Fairy Ocarina, instead, travel forward in time to become adult Link then get the Fairy Ocarina.
This is quite amusing, the cinema of Link and Saria shows adult Link(of course) and throughout the cinema the game 'crushes' Link to try and make him the same size as child Link.
Unfortunately, whilst you may actually have the Fairy Ocarina as an adult, when you use it Link pulls out the Ocarina of Time. Child Link pulls out the Fairy Ocarina though.Before you get the Fairy Ocarina put the OoT on a c-button, after you get the Fairy Ocarina the OoT will still be on the c-button and still is the OoT, the Fairy Ocarina is in your inventory. This can be seen if you are child Link as when you press the c-button the OoT is on he will pull out the OoT rather that the Fairy Ocarina which is only in your inventory.Once you put the Fairy Ocarina onto a c-button the OoT is gone for good.