Spell Trigger

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A spell trigger is a phrase uttered by a spellcaster to signal that he or she is preparing to cast magic, indicating that the caster is making the transition from mundane to arcane or divine. It's sort of like clicking off the safety on a gun. This prevents conversations such as "So I popped out of nowhere and pointed to the minotaur like so and went "Lightning Bolt!" and... oh crap! Dude! I'm so sorry!"
The aura around a potent spellcaster often reacts to a spell trigger, sometimes sparkling with mana sparkles.
Many spellcasters use one particular to themselves, though a generic one will work (though these are discouraged).
There is an awesome online resource here. -->
Generic Spell Triggers
"Abracadabra!" (as generic as you can get, often used by mundanes who get magic)
"Alakazam!"
"Bippity Boppity Boo!" (Fairy Godmother-Cinderella)
"Hokus Pokus"
"Klaatu Barada Niktu!"
"Klaatu Barada Necktie!"
"Gunter glieben glauchen globen" (Rock of Ages, Pretty Fly For A White Guy)
"Beetlejuice! Beetlejuice! Beetlejuice!"
"Chuckle, Watch This."
"Pull My Finger"
Characters' Spell Triggers
Aagha Nel Foula Gracalie "Ha ha ha HAH ha ha ha!"
Audrea Daleos "Blusey Bruisey Woozy Hatchie Tatsie!" 
Cheri Karmuliken "Abbrity Drabbit Fitz-blitzity Bam!"
George Tulwyn
Gina Atakares "Gonka Donka Gedonkity-donk!"
Kandi Kayne "Poppin' Pingle Sweety Eaty!"
Kristara Haleven
Marsilla D'uvoinne "Knowledge be my Sword and Shield!"
Newall Dragonard
Niffle
Nigel Stormseeker
Otto von Schnitzel
Professor Sarn "Explo Dexply Kathoomity Boom!"
Sara Winter of Kasteban
Tatara Somart "Timuvay Nihaulgun vlo bula! ( Blessed be the Final Passage -In Thalosian )"
Tierken the Burner  "Burn burn burny bitch BURN BITCH BURN!!"
Game Use
For those who are really worried about it, saying this is an immediate action. It is more of a character thing than anything else. For those with the "Silent Spell" feat, this part is silent too, though the caster still has to think it.