An oxymoron is a figure of speech made up of words that usually have completely opposite meanings. As a writer, you can create a character who has a tendency to use oxymorons in his or her speech. Even though oxymorons are pretty much self-explanatory, I will elaborate a bit on each one. I will also give an example sentence of how the oxymoron is used.

I'm not saying that it is incorrect to use an oxymoron. I sometimes find the terms we use to describe things hilarious, but I still use these terms myself. Then I think about what I have said and begin to wonder just how these figures of speech began.

a capella with music
When a song is sung a capella, there is no musical accompaniment.
If a song is done a capella with music, then it isn't a capella.

a fine mess
Fine means perfect or elegant. A mess is something dirty, untidy, and disordered.
That is one fine mess you've gotten yourself into!

a little big
Little means small. Big means large, or not little.
You are such a little big boy!

a little pregnant
In this instance, little means just a tiny bit. Pregnant means with child. I'm not sure how one can be just a little pregnant.
Janine turned out to be just a little pregnant.

a new classic
A classic is an established work of literature or art. It has proven itself to be of the highest quality.
Harry Potter and the Sorcerer's Stone is a new classic.

absolutely unsure
Absolutely means completely sure, without exception. Unsure means not sure.
She is absolutely unsure about which college to attend.

abundant poverty
Abundant means plentiful, rich, overflowing. When one is living in poverty, one just doesn't have much of anything.
Because of the family's abundant poverty, they lived in a small shack.

academic fraternity
Academic means scholarly, it pertains to learning. A fraternity is an organization of male students for social purposes.
Gary was nervous about his upcoming initiation into the academic fraternity.

academic sorority A sorority is the same as a fraternity, only a sorority is made up of female students.
Leah is the president of the academic sorority.

accident alert - An accident is never planned or expected, it just happens. An alert is a warning put out in advance of a storm or impending disaster.
An accident alert had been issued when the accident took place.