Culear is a very colloquial and vulgar verb in Spanish, roughly translating to "to screw" or "to have sex." It's a strong word that you wouldn't typically hear in polite conversation or many mainstream songs.
In the context of "Mala Novia," the lyric "Sabiendo que te volé pa'cá nomás para culear" directly translates to "Knowing I flew you over here just to screw." This explicit use of the word immediately sets a raw and provocative tone for the song, highlighting the casual and physical nature of the relationship described.
Calle 24's "Mala Novia" is a super blunt look at a complicated, secret relationship. The song describes a woman who tells her parents she's going to work, but she's actually meeting up with the singer "pa' culear" [to hook up]. She's into OnlyFans "pa' facturar" [to make money], and the singer says she's not a bad girlfriend, but rather that "Solo lo hizo porque él lo hizo también" [She only did it because he did it too].
It's a pretty wild ride, with lines like "La puse en cuatro a la loca" [I put the crazy one on all fours] and her answering her boyfriend "con culpa" [with guilt]. The song even mentions her getting surgery "Pa' quedar más buena" [to look better], but the "vacío todavía no se va" [emptiness still isn't gone]. It's a raw and honest portrayal of a relationship full of secrets and a bit of a rebellious spirit.