Slang

(try to find sources for at least most of these, especially the more obscure ones)

Common slang

 * "Fairy-fail." This is an extension of the regular word fail to include fantasy-based alliteration.
 * "It's on like fairy song." This seems to be an extension of the normal phrase it's on, used when a character is particularly angry at another.

Substitutes for curse words or insults

 * "Oh, rats. I forgot." Rat replaces drat.
 * "Oh hex no." Hex seems to replace heck, though it could also be any other stronger profanity.

Character-specific puns

 * "Tea-riffic" is what Maddie replaces terrific with.
 * "Charm you later" is what Daring says instead of See you later.

Classes, stores, and objects

 * The Glass Slipper