The presence of linguistic diversity in the cinematographic product cause several difficulties to the translation due to the restrictions of constrained translation and to the complexity of the dialects transfer from English to Spanish. This deductive study, based on the comparison of the original and dubbed version of the film South Park: Longer, Bigger and Uncut (Parker, USA, 1999), aims to show the obstacles translators may find and the wide range of possibilities they also have when dubbing slang. Therefore, this article explores several basic concepts related to slang (such as insults, sexual terms, euphemisms and dysphemisms) and the way they are dubbed.