Bah-ti-dão! is a playful, onomatopoeic spelling of batidão, which literally means "big beat" or "heavy rhythm." It's often used in Brazilian music to describe a strong, infectious dance beat.
In this song, it's used at the end to emphasize the energetic, danceable nature of the track, almost like an exclamation of excitement for the music. It's a fun, unique word that captures the vibe of the song.
This song, "Quem Ta Na Minha Cama" by Manu featuring Dennis, is a really fun and feisty track about a confusing on-again, off-again relationship. The singer is totally fed up with someone who keeps saying they're over him, but their actions tell a different story.
He's like, "Eu sou passado né? Você me deu o pé" [I'm in the past, right? You dumped me] and "Eu 'to botando fé que você não me quer" [I'm believing that you don't want me]. But then he asks the big question: "Então por que 'cê 'tá na minha casa?" [So why are you at my house?]. The whole song is a call-out to this person who "Fala que não vem, fala que não quer, fala que não beija, fala que não ama, fala que me odeia, fala que não transa" [Says they're not coming, says they don't want to, says they won't kiss, says they don't love, says they hate me, says they won't hook up] – but then he drops the blunt truth: "Mas quem 'tá na minha cama quase toda a semana" [But who's in my bed almost every week]. It's a hilarious and relatable take on someone who can't make up their mind!