Annoy Xemnas!
Let's start with Mansex cuz why not?
Ask how many zebras were killed to make his coat during the final bossfight
Mourn the lost zebras
Call PETA on him
Say his coat is ugly
Put it in the laundry with a red shirt
Invite the Akatsuki over for dinner
Serve shark fin soup for Kisame and tell him it was Xemnas's idea
Get the Akatsuki and Organization XIII to unite as one awesome crossover!
Ask who's going to be in charge and watch the two leaders kill each other
Tell him Darth Vader wants his lightsabers back
Bum bum bum bum ba ba bum ba ba bum! (Or however the beat to the Star Wars theme song goes)
When he turns into that dragon thing, shout FUS ROH DA! and sing the Skyrim theme song until you feel epic
Tell the Dragonborn
Refer to him as Spyro from now on
Replace the Organization XIII members with Skylanders
Hope he doesn't send Saix after you for that
Run, run away!
Run to the Pridelands and hide behind a herd of enraged zebras
Rip out someone's still beating heart and give it to him as an apology gift