In reading about some of the concepts underlying language, I thought it would be interesting to apply the origins and purposes of language to slang usage. 'Slang' refers to the informal expressions of speech, like cursing or grammatically incorrect statements (e.g. ain't, f'inna). Undoubtedly, we all engage in slang from time to time. Slang can be an outlet for humor, a release of frustration, or for some it is the opportunity to develop a rebellious spirit. Regardless of its expression, slang talk has some interesting psychological backgrounds.
Slang usage serves a key social purpose in that it can help to solidify group identities. To some, slang represents the ability to talk in a way that is distinct from the norm, which may help people identify and become intimate with others who are not accepted, appreciated, or integrated with the "norm". This is a crucial function because finding people to be intimate with is an important innate goal for humans.
Positive reinforcement is the driving force behind the habit of slang talk. If someone's goal in a given social context is to achieve intimacy, they will tend to replicate those behaviors which elicit the best responses from the peers in that social group. So if the members of a given group are prone to rejecting the standard formal language in exchange for more slang-type speech, it becomes more likely that a person attempting to be welcomed into this group will use slang terms in his speech.
My concerns about the use of slang relate to the theory of linguistic relativity, which maintains that some parts of language help to mold our thought processes. If thought processes are related to language, what are the possible effects of habitually talking in slang on the way we think? In my opinion, there would be no distortion because slang talk is highly generative, just like normal speech. Slang talk involves high levels of creativity and complexity, which are the hallmarks of human language.