Maniquí translates directly to "mannequin." It's an intriguing word because it's not commonly found in song lyrics, making it stand out.
In "Maniquí," Nicky Jam uses this word as a powerful metaphor to describe a person who has become superficial and emotionally cold. He sings, "Yo no quiero estar con un maniquí" (I don't want to be with a mannequin), implying that his partner has lost her warmth and authenticity, becoming as lifeless and empty as a store display figure. This metaphorical use gives the word a deep, critical meaning within the song's context.
Nicky Jam builds this whole song out of one insult, and he starts with the weather. "El clima está caliente y tú tan fría" ("The weather's hot and you're so cold") is the opening line, and he keeps turning the thermostat down from there: "Temperatura hielo" ("Ice temperature"), then "Siempre que te toco me congelo" ("Whenever I touch you, I freeze"). The complaints underneath the metaphor are much smaller and much funnier than it is. "Y te maquillas más de la normal" ("And you wear more makeup than usual") is a genuinely petty thing to put in a song, and "Y pa' colmo estás pidiendo que me case" ("And to top it off, you're asking me to marry you") tells you exactly how invested he is.
The title does the real damage, because he means a mannequin as retail rather than as art. "Pero pa' tu size ya no hay mercancía" ("But there's no merchandise for your size anymore") and "Tú no eres la misma que saqué del case'" ("You're not the same one I took out the box") put her on a shelf he picked her off, which is a colder line than anything he says about ice. Next to that the hook is almost courteous: "¿Qué te pasó, mami? Que tú no eras así" ("What happened to you, babe? You weren't like this"), and then "Yo no quiero estar con un maniquí" ("I don't want to be with a mannequin"). He asks that question six times and never once leaves room for her to answer it.