I wanna crush my friends balls but I'm to nervous

Ok so this is a crazy story but this seems like a good sub to tell it also it may be a bit long and a bit disjointed, sorry.

So I was on tinder and stumbled upon my friends profile, curious I scrolled through his profile and saw that it said he was just looking for women who wanted to try ballbusting and to contact him on his snapchat. I had absolutely no idea what ballbusting was so I hit him up on an alternate snapchat account and asked him about it. He told me it was a fetish where dudes are into women hurting their balls.

Now normally I'm a pretty sweet woman, but I'm a huge sexual sadist, I love to cause pain, wich absolutely scares most men off, I'd barely ever get to act out the vast majority of my fantasies, he was one of the few people who knew I was a sexual sadist so I'm not really sure why he didn't ask me to crush his nuts. I asked him if he'd ever been ballbusted and he said yeah a few times. I'd only ever hit him there once, I nut taped him pretty hard a long time ago and so I asked if he'd ever been nut tapped, he told me the story of when I nut tapped him but he massively embellished it. I asked what he thought of the girl who nut tapped him and he told me that he always wished I'd do it again. I then asked how he'd feel if that girl suddenly ballbusted him and he said he really wished any of his female friends would ballbust him.

Well I kept asking him about his fetish and at some point he said he loved unexpected ballbusting and that he wanted a woman to make him beg and humiliate him.

Well I stopped talking to him on this alt account, told him I'm sorry but I'm not interested. But I kinda actually wanna ballbust him, He said he's super into suprises so I want it to be a suprise if I do ballbust him. I've been trying to work up the nerve, I keep having him come over to my house to hang out and I've joked about hitting him in the balls so many times, and I can see he always gets super hard but I always loose my nerve to actually bust his balls. He's even said things like "I don't believe you" and "yeah right".

Idk I really wanna bust his balls, and I know he wants me to bust his balls but I always loose my nerve, what should I do? As I'm writing this he's currently chilling on my couch and I want to just walk over there and punch him in the balls, but I'm to nervous