My college ex-girlfriend had a friend named Adam who was the super-open-about-sex kinda' guy. He was a very cool guy most of the times, but he used to cross the line with his female (and male) friends way too often by making very sexual remarks about them.
However, he also had this very "normal" vibe while saying and doing those things. He didn't sound like a perv or like a creep. He sounded... normal; like he was talking about anything but sex.
One day, my girlfriend wore some quite sexy black leggings (you could even see her undies). I was the first guy to see her in the morning so I didn't waste my time and grabbed that ass. We went separate ways to take our respective classes. A couple hours later, I went to her classroom to pick her up. The professor was gone, but she was with Adam and a couple of other students (minding their own businesses). I waited outside, as I didn't want to be THAT boyfriend who ruins good talks with friends when he arrives.
But then, out of nowhere, she turns around and let him see her ass for some good 10 seconds and then he quickly spanks her. Right in front of me! They both laughed and continued talking for like one more minute; until I came in like if nothing had happened. We both said bye to Adam and went our way.
I wasn't as open with "sharing" as I'm now, so immediately after we left, we had a huge fight and I got quite jealous every time she was around him. We broke up like a month later (not because of this, but many other things). Now that turns me on and I have even pictured having wild sex; but at that time, well; I didn't take it that well.
