This is a pet peeve of mine but...is 'wanna' a commonly used word in the USA? It grates whenever I read it as it's rarely used where I am.
"Wanna" is called a "contraction" or "slang", probably originating from "want to" and "want a" both pronounced like "want'ta". (For example, I am from Sacramento, which is often pronounced as "Sacra-minnow". Also see "shoulda woulda coulda".) Quite common in Northern California at least. Its probably best described as Internet English. The real question is: Does it make it harder to understand? Does it obstruct the goal of communicating information? Or do you normally speak like a 17th Century aristocrat, using archaic words that very few understand, but are probably technically on point? (Sorry, that are veritably apposite.)
I ask because I would like to explore the reasoning behind the conclusion that such words are bad. If they are bad because they hinder effective communication, then so are words that are uncommonly known, I argue. Which seems to pose the argument that we should best speak like simpletons because simpletons, or people that are too pedantic, may not understand the meaning.
'Wanna' has a particular confrontational connotation (possibly a joking one) that I believe was desired here. 'Want to' wouldn't have had the same effect.