Ruborice comes from the verb ruborizarse, meaning 'to blush' or 'to turn red'. It's a less common and more evocative word than simply saying 'ponerse rojo'.
In the song, the singer describes a mysterious woman who contradicts him "por placer, para hacer que un día me ruborice" (for pleasure, to make me blush one day). This reveals her playful, provocative nature and his vulnerability, making it an intriguing and memorable word choice.
Emmanuel's 1989 ballad turns obsession into confession. He opens by admitting he barely knows her — "Aun yo no sé quién es" [I still don't know who she is] — yet "Lo deben saber mis pies" [My feet must already know], because they keep following her anyway, "como las ratas / A la flauta de Hamelin" [like the rats after the Pied Piper's flute]. She lives in the gossip pages, "siempre en portada" [always on the front page], and by the second half he's confronting her directly — "Y quién te crees que eres tú" [And who do you think you are] — without ever getting past the question. The hook, "Mi chica de humo" [My girl of smoke], repeats because that's exactly what she is: there, then gone, impossible to hold.