Arrechura is a very interesting and versatile slang term, particularly common in some Caribbean Spanish-speaking countries like Venezuela and the Dominican Republic. It can mean intense anger or fury, but it also frequently refers to a strong sexual desire or horniness.
In the context of this song, the line "Me acuerdo cuando tú tenías tu arrechura / Que me llamaba' cuando estaba en baja / Pa' que te la suba" suggests a double meaning. It could mean she was angry and called him to cheer her up, or more likely, she was feeling horny and called him to satisfy her. This dual interpretation makes the word particularly enticing and memorable for learners.
Amenazzy and Ntg's "No Se Olvida" is all about a guy who just can't get over a past fling, even though he knows this girl isn't good for him. He remembers when she used to call him when she was down, needing him to cheer her up: "Me acuerdo cuando tú tenías tu arrechura / Que me llamaba' cuando estaba en baja / Pa' que te la suba" [I remember when you were upset / You used to call me when you were down / For me to lift you up].
He's confused about why she's stopped contacting him, wondering what people might have told her. He's still hung up on what she did to him, repeating, "Lo que me hiciste no, no se olvida, no se olvida" [What you did to me, no, it's not forgotten, it's not forgotten]. He even admits she's right about herself: "Y tienes razón, mami, tú no eres buena" [And you're right, mami, you're not good]. Despite all this, he's still chasing her, asking "¿Qué es lo que pasa, mi amor, que no me frena'?" [What's happening, my love, why don't you stop me?], and he's clearly still very attracted to her, calling her "mi nena tú está muy buena" [my baby, you're very hot]. It's a blunt and honest look at a guy stuck on a girl he knows is trouble.