Temblar literally means "to tremble" or "to shake". It's a vivid verb that can describe physical shaking due to cold, fear, or excitement.
In this song, Cris MJ uses temblar in a suggestive and provocative way, singing "Voy a ponerte a temblar las piernas abierta'" (I'm going to make your open legs tremble). This implies a strong physical reaction, likely from intense pleasure or excitement, making it a memorable and impactful word in the context of the lyrics.
Cris MJ turns a pickup into a boast on 'Temblar' ('To Tremble'), stacking breathy ad-libs over a slow reggaeton groove. He picks her up in an armored car — "Le caigo en la blinda' a buscarte, mi reina" ("I pull up in the armored ride to get you, my queen") — and promises a night entirely on his terms: "Voy a ponerte a temblar las piernas abierta'" ("I'm gonna make your legs shake spread open"). The steady hook "No te va pasar nada" ("Nothing's gonna happen to you") sounds like reassurance and warning in the same breath, and the closing line turns the whole song into a flex about experience: "Le meto desde chamaquito" ("I've been putting it in since I was a kid").