At a subculturey party, I made friends with a girl, and when I had to leave I went to say goodbye to her and ask her for a hug. She was talking to someone else who I didn't know at all, and after I hugged her, he went for a hug too. He was too close for me to think of a way to evade him beyond the overtly dramatic "ducking and dodging", so, what the heck, it was just a hug. But then instead of just hugging me he did a weird thing where he alternated the relative position of our heads a couple times. Then he kissed me on the cheek.

I still didn't know this guy at all, so, maybe that was a weird cultural thing or something, but I said "I was not comfortable with that, you shouldn't do that". Still could have been an innocent misreading, if he'd let me go and said "sorry" that would have been the end of it, but instead he said, "Well, I'll probably never have the chance to do it again, so that works out" - which made it Decidedly Sketchy and not-OK; kissing people who don't want to be kissed is not ever a case of things working out, trying to laugh off someone's discomfort is not cool, and the fact that he said this anyway cast all of the things he'd already done that were sketchy in a retroactively worse light.

(This is by far the sketchiest thing that has ever happened to me at a subculturey meatspace event, to be fair. Next closest thing was when I had to verbally signal the end of a hug and the guy let go instantly and apologized, and that's the only other thing I can think of.)