In FFX-2, dress spheres are made by a dirty mail company. When Yuna and co. put them on too much, they turn into mail ladies. Doomed to forever roam the earth being chased by little doggies.
If you backslap Auron in the face, you get the Rick Ross weapon, which has the ability to Hustle. This instantly steals anything from an enemy, and rarely instantly kills anything.
In the first mission of FFVII, if you spend 100 minutes more than you're supposed to, Ifirt will use a giant metomathingything and blow up everything. That includes Ultimecia.
If you defeat Nemesis from FFX without damage, you unlock a new airship location, called 'Wendys'. Home of the strongest baked potatoes in all of Spira.