Why would you stop him?
I'm pretty sure if one of my friends walked in on someone tongue fucking me and they tried to stop it they would no longer be my friend.
Well thats YOUR kink then... personally that scene was stupid beyond belief to me, you meet that hot neighbor (before you know she is a gutter trash whore), and think she is hot, you meet the black dude who "claims" he is your buddy and asks to borrow 50 bucks since your such "pals"...
Later at the party you come across a scene that doesnt seem like BDSM play, but downright rape... your PC tries to stop it, and your "buddy" threatens to shove his dick down your throat if you dont let the rape continue... WTF ??
1. What kind of friend is that ? He should have come back to his senses and realized he's being a rapist asshole !!
2. The MC cant chose to be a man and fight this loser ? I would have kicked his ass, or gotten my ass kicked, but if he tried to stick his dick in my mouth he was losing it like Andy Duprae from Shawshank Redemption said...
Then to make matters worse the stupid bitch comes to your apartment later and says "haha I am a cheating whore that loves to be raped and abused and treated like garbage, I was never in any danger... Also I mostly love black guys huehuehue" (she became brazilian for a bit). And gives you a blowjob too, to show what a charming interesting woman she is... *groan*