If the person you were dating had the tendency to share intimate details of your relationship such as sex.
Most Helpful Guy
If it were kissing, then I don't think I'd have a huge problem with it, unless it were insulting or really really personal.
Admittedly, if she made me sound really really great (but only in general), like, "he's a spectacular kisser," then I'd be less embarrassed, but only slightly. Getting into graphic detail, angles, sizes, etc, is crazy. That's a private thing between two people. Why do all friends need to know? I honestly don't talk about with my guy friends, and it's a stereotypical guy thing to do. It's none of their business what I do or don't do, unless I'm accountable to them.