Ok so I know the title makes me sound like the asshole but hear me out.

Sorry for any formating (I'm on mobile)

Ok so my best friend (let's call him Bob) he is kind of a fuckboy, but that's not the problem, the problem is that he has made it his goal to have sex with this girl (let's call her Susan) for a new years party, that us and a lot of other friends are going to be attending. The thing is they are both sleeping at my place, because they both live far away from where the party is, and I have specifically told Bob that nothing is going to happen at my place, but he won't take me seriously and he just says "what happens happens". I told him over and over again that it wouldn't be happening (were both 17 and my parents would be home). But he just won't accept no for an answer.

WIBTAH if I said that they wouldn't be allowed to sleep at my place if anything was going to happen, between them.

It also needs to be said that he normally doesn't understand when he has stepped over the line (especially if it's over the phone, he has done that a couple of times)