Encaramó comes from the verb encaramarse, which means to climb on top of something or someone, often in a playful or intimate way.
In the song, Myke Towers sings, "Encima se me encaramó," which literally translates to "She climbed on top of me." This word is interesting because it's less common than simply saying "subió" (climbed) and carries a more suggestive, playful, and intimate connotation, hinting at the physical closeness and flirtation between the two people.
Myke Towers lays out the whole plan before anything happens. 'Si se nos da el momento' [If the moment comes], he says, then walks through exactly what he'll do: 'Empiezo besándote lento' [I'll start by kissing you slowly], wherever she wants, for as long as she wants. He's upfront about the terms too. 'Los sentimientos no mezclo' [I don't mix feelings], and 'Mami, por más que quisiera' [Mami, no matter how much I might want to] doesn't change that. It's a hookup pitched like a contract, spelled out line by line before either of them commits to it.
The verse turns the setup on its head. 'Ella quiere enamorarse' [She wants to fall in love], he admits, but he says outright that he doesn't believe in love at all. What actually gets him isn't a line or a plan, it's her crying. 'Yo le saqué una sonrisa a aquella carita triste que lágrima' derramó' [I got a smile out of that sad little face that was in tears], he raps, and after he tells her he's only offering friendship, she doesn't take the hint. 'Encima se me encaramó' [On top of that, she climbed all over me], he says, sounding pretty pleased about it. By the outro the whole crew is bragging outright, warning off any imitators with 'No lo intenten en sus estudios, cabrone' [Don't try this in your studios, you bastards], exactly the kind of line a group throws in when they already know the song is a hit.