Untermensch literally translates to "subhuman" or "under-man." It's a historically charged and provocative term, famously used in Nazi propaganda.
In the context of Farid Bang's lyrics, he uses it as an extreme insult, calling someone a "Bike-fahrender Untermensch" (bike-riding subhuman). This word is highly impactful due to its controversial history and its use here to deliver a strong, aggressive diss, making it memorable and unique to this type of rap.
In "Johnny Fontaine," German rapper Farid Bang delivers a powerful statement of dominance and independence. The song is a classic example of a "diss track," where he asserts his superiority over the entire German rap scene. He portrays himself as a physically imposing figure, a "Muskelmensch" (muscle man) who only needs a microphone and a protein shake to succeed. He boasts that his raps are so destructive they can end other artists' careers.
The central theme revolves around the line, "ich bin nicht Johnny Fontaine" (I'm not Johnny Fontaine). This is a reference to a character from the movie The Godfather who relies on mafia connections for his career. Farid Bang uses this to declare that he is self-made and doesn't need protection or favors from anyone. He contrasts himself with other rappers who he claims are "fake" and have to pay for protection, while he built his success through his own strength and business sense, even referencing a past of selling drugs to celebrities.