Chanchú is a colloquial and somewhat playful term, particularly used in Puerto Rico, that refers to trickery, shenanigans, or a shady deal. It's not a word you hear every day, making it quite memorable.
In the song, Residente uses it to dismiss his opponents' outdated tactics, saying, "a ese truco hace mucho chanchú" (that trick has a lot of trickery/shenanigans). He implies that their moves are old news and full of deceit, highlighting his own authenticity and superior flow.
Residente teams up with two rap legends from different generations — Puerto Rico's own Vico C and Brooklyn's Big Daddy Kane — for a freestyle built entirely around bragging rights, with no real story beyond who still has the sharpest bars. Residente opens by casting himself as "el rey escupiendo spray" ("the king spitting spray"), a graffiti writer tagging "todo el highway" ("the whole highway") with his verses. Big Daddy Kane arrives mid-song for a full guest verse in English, warning any rival that "Real hitters keep the strap for any type of beef or spat" — old-school swagger dropped straight into the middle of a Spanish track. Vico C closes it out with the relentless hook "Soy el matatán, matatrack" ("I'm the top dog, the top-dog-track"), repeating "Matadero en mi área cuando tiro boom bap" ("Slaughterhouse in my area when I fire off boom bap") until the beat runs out. It's less a song about anything than three rappers, in two languages, taking turns proving it.