Patrás' is a colloquial and shortened form of "para atrás," which means "backwards" or "behind."
In the song, it's used to describe how fair-weather friends disappear when problems arise: "Corren todos sin mirar patrás'" (They all run without looking back). This informal usage makes the lyric feel more authentic and relatable to everyday Spanish speech, capturing a sense of urgency and abandonment.
Cruz Cafuné's "Cuando Estoy Mal" is a relatable anthem about fair-weather friends. He feels like his phone is broken, saying "Nadie me checkea cuando estoy mal" [Nobody checks on me when I'm bad] because when he's down, no one is around. It's like he's "sin megas" [without data] and can't connect with anyone.
He points out that people only want to be around for the good times: "Solo quieren verme vacilar / Cuando hay party, cuando hay money cuando, hay tal" [They only want to see me have fun / When there's a party, when there's money, when there's this or that]. But when problems hit, everyone runs. He feels like he only has a few true friends left, and even one of them "se fue pa' Senegal" [went to Senegal]. It's a blunt look at how loneliness can feel even when you're surrounded by people who claim to be there for you.