Péssimo Negócio translates to "Terrible Deal" or "Bad Business". It's a striking phrase that serves as the title and a recurring theme in the song, making it highly memorable and central to the lyrics.
In the song, Dilsinho uses this phrase to describe the protagonist's regretful decision to trade a lasting love ("um pra sempre") for a fleeting adventure ("uma aventura"). It powerfully conveys the foolishness and heartbreak of making such a poor exchange in matters of the heart.
"Péssimo Negócio" is a song about regret, sung by a man who is putting a price on what he lost. It took him a thousand right words to win her over, and only one wrong one to lose her. It took him a long time to fall in love, and a single minute to end it.
The song turns that regret into the language of a bad deal. He asks if you know anyone who threw away a diamond, then admits he did exactly that. He asks who would trade a great love for one moment, then admits he made that trade too.
In the chorus he talks straight to his own heart, as if it were the business partner who signed off on the deal. Swapping "forever" for "sometimes", an adventure for a real passion. That is the terrible business of the title, and he already knows the numbers do not add up.
The ending closes the door. She says she does not want to talk anymore, and all that is left is the Brazilian expression "agora dorme com essa", which means go ahead and sleep on it, live with what you did. Recorded live, so you can hear the crowd singing the regret back at him.