As Jesus vs. Santa became more popular, Parker and Stone began talks of developing the short into a television series. Fox refused to pick up the series, not wanting to air a show that included the character Mr. Hankey , a talking piece of feces.  The two then entered negotiations with both MTV and Comedy Central. Parker preferred the show be produced by Comedy Central, fearing that MTV would turn it into a kids show.  When Comedy Central executive Doug Herzog watched the short, he commissioned for it to be developed into a series.  
Throughout the entire run of the South Park series, there have been a few instances where Cartman spoke languages other than English quite well and he does seem to be fluent in Spanish and speaks very good German (for the sake of South Park). For example, in "The Passion Of The Jew", when Cartman dressed as Hitler, while rallying outside the theater presenting "The Passion" with a group of Christian followers, he began chanting hateful comments to Jews in German such as " Es Ist Zeit zu säubern " ("It's time to cleanse), while the crowd replies "" Wir müssen die Juden ausrotten! " ("We must exterminate the Jews!"). Next, Cartman exclaimed " Es ist Zeit für Rache! " ("It is time for revenge") and the crowd replies "Wir müssen die Juden ausrotten!" ("We must exterminate the Jews!"). While Cartman didn't necessarily pronounce the German words correctly, it was pretty clear that he understood what they meant in English and his followers did not. However, in " Pandemic ", the boys decided to start their own Peruvian band to earn some spending money. When they spotted a real Peruvian band "stealing their spotlight", after the other boys first confronted them in English and the band members continued to play as if they didn't hear them (since they didn't speak English), Cartman began yelling at them in Spanish, generally telling them to stop playing in their area. The band paused for a long second in confusion, then continued to play. This then prompted Cartman to repeat what he originally told them in Spanish and out of anger he even snatched one of their instruments away and threw it off into the distance. Also, in " My Future Self 'n' Me " he spoke to Mexican workers in fluent Spanish, suggesting that he is, in fact, fluent or knows a few phrases. He also speaks French to Clyde in " Make Love, Not Warcraft " as "Voulez-vous coucher avec moi, Clyde?", or "Would you like to sleep with me, Clyde?". This, however, is a line from the song "Lady Marmalade", and considering the meaning of the phrase, likely means that Cartman does not actually speak French. Granted, there really hasn't been much focus on this particular talent of Cartman's (since most of the story plots don't focus on it) so there's virtually very little known as to how he learned these other languages so well at such a young age. It's possible that his mom Liane Cartman may have personally taught him the other languages, as was revealed in " Hooked On Monkey Fonics when she purchased a educational game that helped Cartman to improve his spelling skills.