Quedantes is a popular Mexican slang term for the people you are casually dating, similar to a 'situationship' in English. The word comes from quedar, which means 'to meet up'.
In the song, Natanael Cano sings about his love interest's other suitors, from businessmen to traffickers, calling them her quedantes. He isn't intimidated, confidently stating that she'll be with him in the end. It's a perfect word for understanding modern, informal dating culture in Mexico.
In "Madonna", Mexican corridos star Natanael Cano and Óscar Maydon team up to brag about spoiling a girl who accepts nothing less than extreme luxury. The opening line sets the mood immediately: "Yves Saint Laurent, y si no es Dior que no la llamen" ("Yves Saint Laurent, and if it's not Dior, don't even call her"). She won't touch cheap drinks either, sipping alcohol only if it comes mixed with high-end bubbly ("Lady Gaga, no toma si no es con champaña" ["Lady Gaga, she doesn't drink unless it's with champagne"]). Her other suitors range from businessmen to cartels ("de empresarios a traficantes" ["from businessmen to traffickers"]), but Natanael shrugs them off as total nobodies. He is so hooked that she tamed his wild side ("Tú domaste mi instinto animal" ["You tamed my animal instinct"]), and his solution is simple: throw endless cash at her feet.
The flexes get ridiculous, and that is half the fun. He is ready to buy stacks of luxury watches ("¿Cuántos Rolex te ocupo comprar?" ["How many Rolexes do I need to buy you?"]) just for a single kiss, and he even offers to wire cash directly to her parents ("Le mando dinero a tus papás" ["I send money to your parents"]). Óscar Maydon jumps in to admit he had to bust his back to afford an ultra-expensive Birkin bag ("me pegué un tiro pa' comprarla" [literally "I shot myself to buy it", a Mexican slang idiom for going through hell or struggling hard to get something]). In Mexican Spanish, "lana" means cash ("No te preocupes por la lana" ["Don't worry about the cash"]), and "güerita" is an affectionate term for a light-skinned or blonde girl. Calling her "Madonna en la actualidad" ("Madonna nowadays") with a "flow rockstar" sums up how he sees her: untouchable, stylish, and expensive to keep around, even while she leans over to make out with him while he drives ("me besa al manejar" ["she kisses me while driving"]).