"Losing four fights to the mobs will put Mezz in "Slut mode." Among other things, this will change the gameplay of Entertainment District I to stealth. If caught three times, there will be a small, non-full-cg scene. If THIS happens four times, there will be a final small, non-full-cg scene and a game over."
Mobs in this case is just the hyena enemies, lose to them 4 times and you'll be in slut mode.
Slut mode works by changing gameplay, and enabling and disabling the availability of some scenes. That's all.