Mannerisms

Among other things, Selphie is characterized by certain language mannerisms, some of which are exclusive to her in Final Fantasy VIII. They were most likely given to her to mirror her spunky, carefree, talk-before-you-think personality, and often result in hilarious quotes.

Blow to Smithereens
Selphie uses this expression often, especially when referring to what she would like to do to President Deling's private train or the Galbadian Missile Base.

Booyaka
"Booyaka", in Selphie's words, is her very own lingo that she is trying to spread ~~(WTF...)~~. She uses it in her diary, mainly as a greeting, but comes to realize that, strangely enough ~~(...right)~~, no one else does.

Bummer
When things go wrong, Selphie is likely to be found blurting out typically cute, hyperactive expressions such as "Super-Duper-Mega-Bummer" (taken from a quote in Timber, when the party finds out there are no train tickets for the East Academy left). She also uses the word on its own several other times.

Heeey
Selphie has her very own, slightly lengthier version of "hey!" (upon realizing something, for instance). I always imagine her "heeey...!"'s as sounding like something coming from a person on a pot high.

Tee-hee
Often said by Selphie whenever she is grateful or happy about something, like when Squall opens the door leading to the window corridor inside trains.

Whoo-hoo
"Whoo-hoo" is, by far, Selphie's more hysterical language mannerism. She uses it many, many times, often sounding like a mad person (like in the Missile Base, when the team finishes a couple more Galbadian soldiers and she goes "Whoo-hoo! Let's keep movin'!", causing even Irvine to think that she "can be a little out of control at times"). A personal favorite, this seems to always be there whenever a funny quote comes up.