Gouttière literally means "gutter". While it might seem like an ordinary word, its use in the phrase "chat de gouttière" (alley cat or stray cat) is particularly evocative and interesting.
In the song, the narrator laments, "redevenu chat de gouttière" (you became an alley cat again). This phrase beautifully captures the idea of the cat (and metaphorically, the person) returning to its wild, independent, and perhaps unfaithful nature after a period of domesticity. It's a common French idiom that paints a vivid picture of someone who can't be tamed.
Have you ever felt completely played by someone you cared about? MPL's "Petit Chat" [Little Cat] is all about that feeling, wrapped up in a story about a stray cat. Our singer finds this lonely "petit chat" on the street, collarless and looking pitiful, with a "moustache poudrée de lait" [milk-dusted mustache]. He takes it in, feeling like its "roi dans l'heure" [king in an hour], only for the cat to break his heart and revert to a "chat de gouttière" [gutter cat].
This isn't just about a cat, though. It's a metaphor for a frustrating, on-again, off-again relationship. The cat keeps coming back, and the singer, despite being left "seul au bord du lit" [alone at the edge of the bed] "au moins cent fois" [at least a hundred times], keeps forgiving it. He's tired of the broken promises and the cat's apparent inability to love anyone, only going "où on te donne des petits plats et des caresses" [where you're given little dishes and caresses]. The singer's frustration builds into a dark, almost humorous threat: "Je t'arracherai la vie neuf fois s'il le faut" [I'll rip your life out nine times if I have to]. It's a blunt, dramatic expression of how much this person has hurt him, and a powerful way to end this intense, relatable story.