Mitonnes comes from the verb mitonner, which means "to simmer" or "to cook slowly". However, in French slang, especially in informal contexts, mitonner also means "to lie" or "to make up stories", often with the implication of doing so in a manipulative or deceptive way.
In the song, Aya Nakamura sings, "J'suis paranoïaque j'sais qu'tu mitonnes" (I'm paranoid, I know you're lying). This use of mitonnes adds a layer of suspicion and distrust, highlighting the narrator's frustration with her partner's evasiveness and dishonesty. It's a less common, more colloquial word than mentir (to lie), making it more engaging and reflective of contemporary French slang.
Aya Nakamura spends this whole song staring at her phone. She opens almost sweetly, "Salut, salut comment vas-tu?" (Hi, hi, how are you?), then admits she's sent "dix messages" (ten messages) and called "plusieurs fois" (several times) with nothing back. By the chorus she isn't asking anymore, she's ordering: "Réponds, réponds, réponds quand j'te parle" (Answer, answer, answer when I'm talking to you), repeated so many times in a row that it stops sounding like a request.
The line that explains her whole attitude is "Mi-femme mi-attentat" (half-woman, half-attack) - sweet one line, a bomb the next. She isn't begging for anyone back so much as demanding an explanation: "Montre moi ta force vitale" (Show me your life force). Even the silence gets a comeback, "Aya aya aya aya aya yeah" chanted over the beat like she's the only answer she needs.