Infréquentable describes someone considered too dangerous, disreputable, or unpredictable to associate with. It literally suggests that a person should not be “frequented,” making it a striking and memorable adjective.
In the song, Lacrim calls himself "une légende infréquentable", meaning “an unapproachable legend.” The phrase presents him as notorious and larger than life, while also hinting at the dangers surrounding his reputation.
Lacrim and Baby Gang build "Rock" around one blunt hook that switches language mid-line: Baby Gang asks in Italian "Scegli tu se vuoi" (you choose if you want), and the French half answers with "la vie, la mort" (life, death), then "La stick, la Glock" (the stick, the Glock) and "la drogue" (the drugs). The song treats that list as the only menu on offer in the street, and never pretends it is a free choice.
Baby Gang's Italian verse is paranoia and loyalty: a gun and a joint between his fingers, waiting for the door to open, too many friends already lost. Lacrim's French verse is quieter and more tired. He comes home late, smokes, and looks at "la lune derrière la vitre" (the moon behind the window), fed up with people who greet him with a kiss and then betray him. "Les meufs" in his list is slang for girls (verlan of "femmes"). His code is spelled out plainly: "C'est mes amis d'abord" (my friends come first), and "Et si tu trahis nos amis / À midi, t'es mort" (and if you betray our friends, by noon you're dead). He closes by calling himself "une légende infréquentable" (a legend you can't hang around with), someone who went down for robberies.