In this paper I mainly focus on the translation of linguistic varieties that are culture-specific or belong to a socially restricted speech community. These varieties, including slang, often display forms that rarely have equivalents (i.e. forms that are comparable in meaning and scope) in a different language. However, relevant theories on translation (e.g. Catford 1965, House 1997) state that the translator should assure ‘equivalence’ by preserving the semantic and pragmatic meanings across two different languages, and that a first requirement for equivalence is ‘equivalent function’. Accordingly, the translator should keep low semantic and pragmatic transparency – i.e. polysemy and multifunctionality – in the target language (TL), any time they are motivated by socio-pragmatic purposes (e.g. identification with a group, cryptic reasons, establishing intimacy, etc.) in the source language (SL). Therefore I believe that the lexical complexity of slang should be preserved in the process of translation. Lexical complexity in slang formations is first of all due to a marked (Merlini Barbaresi 1988), non-diagrammatic (Dressler et al. 1987) relation between the linguistic sign and its signatum. The cognitive area activated by the slang term includes a vast array of extra socio-pragmatic meanings, which typically belong to the restricted community in which the term is used. Recreating the same effects in a different language community by means of an ‘equivalent’ slang formation is nearly impossible. Still what can be recreated is a comparably complex signans/signatum relation. In this paper, I will examine some examples of free conversation which show slang use, ranging from in-group slang to general slang. I will then establish the status of markedness of some slang expressions (e.g. chick, groovy, hit, etc.) on one or more correlated semiotic parameter(s) (esp. transparency and biuniqueness), and finally demonstrate that marked options generally increase complexity and consequent difficulty in perception, and yet they must be kept in translation to preserve the rich layers of associative meanings normally entailed.