Arromba means "breaks open" or "busts open," often with force. It's a strong, action-oriented verb that isn't used in everyday conversation as frequently as more common verbs for opening.
In the song, the lyrics warn, "tranca direito o seu coração se não ele arromba a porta" (lock your heart properly, otherwise he'll break down the door). This vivid imagery personifies the "ladrão da noite" (night thief) as someone who will forcefully enter and steal your heart, making arromba a memorable and impactful word.
Imagine the scene: it's half past midnight in the bustling city of São Paulo, with the lights of the famous Paulista Avenue shining bright. There's a buzz in the air because a captivating woman has just arrived, and everyone is talking about her. But someone else has noticed her too: the "ladrão da noite," or "thief of the night."
This song tells the story from the perspective of a smooth and confident charmer who sees himself as a heart stealer. He's a collector of loves who has been with all types of women, and he warns that you'd better lock up your heart, or he'll break down the door to take it. In the chorus, he makes his move, telling the woman he knows she wants a kiss and a fling, and asks her to stay a little longer so he can do what he does best: steal her heart.