Macadam literally refers to a type of road surface, similar to asphalt. It's an interesting word because it's not commonly used in everyday French conversation, especially in a song context.
In "Prosper, Yop La Boum!", Prosper is described as "le roi du macadam" (the king of the macadam). This phrase cleverly implies that he's a prominent figure of the streets, a pimp who controls his territory and the women working there. It's a unique way to describe his domain and status.
Meet Prosper, the star of this classic French song! Maurice Chevalier paints a vivid picture of a charismatic man strolling through Paris's famous Pigalle district. With his little green hat and duck-like walk, Prosper is described as the "king of the pavement" and the "darling of the ladies." But what exactly does he do? The lyrics playfully hint that you don't need a degree to figure out his line of work.
Prosper is a manager of sorts, but not in a typical office. He has a "harem" of women who do his "little business" for him all over the city. While they work day and night, he's known for being lazy. His main job is to show up in the evening to collect the profits, taking the big bills and leaving them the spare change. Despite this, the women are said to be crazy about him, even fighting over his attention. The song uses a light, bouncy tune to tell the story of this stylish but ruthless street boss.