This study seeks to investigate "Language-crossing" (or Code-crossing) ( a complex sociolinguistic phenomenon where speakers freely opt to adopt the speech/variety of another group). Sudanese mainstreamers (speakers of Standard Colloquial Sudanese Arabic (SCSA) have been observed to cross to "Randok" ; a variety spoken by an extremely marginalized social group known by their pubic name of (Shamasha). This is a kind of a street language (or anti- language, to borrow Halliday's term) with unique linguistic features. A tiny literature exists whether on "crossing", (coined and pioneered by Rampton), or "Randok" . The phenomenon of mainstreamers crossing to Randok, has, to our knowledge, never before been examined(as a "crossing" act). Drawing on Hewitt (1986), Rampton(1995,1996,1997), Cutler ( 1999), and others, crossing to Randok, has been closely observed, analysed and interpreted; based on a host of sociolinguistic\discourse approaches: Identity formation/construction/shift/representation, code-switching/mixing/choice, New Ethnicities, Anti-languages, etc. Collected over several years, the data encompasses observation, interviews( Randok speakers and (SCSA) mainstreamers of various backgrounds: street venders, intellectuals, academics, writes, linguists, middle class youths, etc.), focus-discussions, and phenomenological materials such as 'introspections/retrospections". Results confirm the existence of language-crossing among (SCSA) mainstreamers to Randok. However, the interpretation of the phenomenon stops short of arriving at a conclusive argument. Instead, Randok crossing has been shown to be supremely interesting, a complex multi-faceted sociolinguistic behavior with a wide range of implications for sociolinguistics, discourse analysis (power relations), language policy, identity theory, knowledge representations, etc. A final distinctive feature of Randok crossing, is the existence of mediators (venders and football fans/journalists) who spread the behaviour among mainstreamers.