If you name your gold chocobo "Aeris" and you go to the City of the Ancients, Aeris will rise out of the water and be like "z0mg Cloudypoo j00 named a ch0c0b0 after meh i wuvvles j00" and you'll have her super secret limit breaks but you can't use her in battle until you defeat homosephiroth who resides in Kalm Town organizing the rainbow festival.