Interesting...
That particular scenario is my hubby's # 1 fantasy I think. Especially after I made the mistake of telling him one time that I'd had a bizzare dream where I was with another woman. He's said that he's perfectly happy with me being the only one he is ever with for the rest of his life, but if he WERE ever to be with another woman, it would be only after I'd had her first.
I've thought about it a few times, but I don't see it ever happening because I am VERY possessive, and I don't like to share. So I thought I might be able to handle it if he just watched, but didn't do anything with the other woman. But then I get stuck on the whole who would it be with issue. I don't think I could be with someone that I wasn't emotionally attached to - so that cuts out strangers. But I don't think I could be with someone I know either because I'd be worried how it would affect our friendship afterwards. I have a couple of friends who shared a guy one drunken night, and their friendship was never the same afterwards. I wouldn't want that to happen.
Good luck with the next weigh in - I'm rooting for you to beat Yank again!