Usually used in excitement, as a positive description of something, or as a sentence in itself. Extra "a"'s can be added to the end of the word.
"SCHWA!You guys are awesome!"
"Rock music is Schwa"
A contraction of the words say and what. Used in informal conversation to denote confusion or disbelief. Can be used interchangeably with the words huh and eh (for Canadians). First appearing in the late 80s, early 90s. Most notably used by Pauly Shore (as the Weasel) in the movie "Encino Man", and Mike Myers in the "Wayne's World" movies.
-Also can be used when cell phone conversation becomes garbled by a spotty coverage area.
Guy: Schwa?! *breaks into a cold sweat*
Mom (on phone): Oh, and honey don't come home without picking up myahr... *garbled*.