David Foster Wallace gave a speech to the Kenyon College graduates in 2005. Here are some examples of “colloquial language” he uses:
-“The nonreligious guy...”
-”...you will be totally hose…”
-”The point is that petty, frustrating XXX like this is exactly where the work of choosing is gonna come in”.
These colloquial phrases and expressions are appropriate in the effect they have: they help the audience (graduates) to feel identified with the language they use and with the daily situations they experience.
In addition, the examples he gives such as the big fish and the small fish or the guys talking about religion (and the colloquial expressions he uses to tell those stories) make up an analogy for kids that help to have a clear, concrete and objective image and idea of the message he is trying to convey.
And, of course, it's also a tool to build up humor and laughter as well as irony.
