I've had it happen once, with a Thai girl. She just kind of jumped on me and it happened. She only grinded my shaft and not the head though. I was OK with it, but would have rathered she hadn't done that, as it does seem slightly risky to me. I could have so easily slipped down a bit and slid inside her unprotected if I had wanted to. I do think back on it somethings and think maybe I should have told her to stop or pushed her off me. But, well, you know how things can go in the heat of the moment sometimes, it all just kind of happened in a quick blur before I had time to think about it. BB never even really got close to happening though, and I never caught anything from it, so alls well that ends well, but I would tend to prefer to avoid a prossie that does anything like this. I'm prepared to risk DFK, RO and OWO, but this isn't really on my 'to do list' when I stroll up to a punt.