Color oops smell

Okay gang help time. I have black box dye in my hair, and plan to keep it that way. BUT. I wanna dye parts of my head other colors, nothing super bright but I would need to lighten it a little so I figured I'd try and color oops it first. How bad does this shit actually smell? Like. When we say it STANK do we mean like. I'm not gunna wanna show my face in public for a few weeks or just it smells chemically? I live with 4 other girls, and will likely be murdered if this shit lingers in our bathroom for weeks so I need to know before I use it.