(nsfw) How do you react when touched at a bar?

Looking particularly for female opinions. I’ve accepted that I am transgender late in life. I am very passable as a woman, but having been raised as male, I try to recognize when I behave or respond in a leaned male way instead of a typical/cisgender female way. I had a new experience and I’d like to know what typical female responses would be.

I was at a bar and a guy was hitting on me. He was cute, fun, kinda drunk, and clearly was hoping to take me home. I made it clear that that wasn’t going to happen but I was enjoying talking with him. Later we’re both leaving the bar and as I walk out I’m saying goodbye to some friends. Then I feel someone behind me has reached between my legs to stroke my crotch. I turned and it was the guy I was talking to. I was surprised, offended, and aroused. I just smiled and continued to say goodbye to friends. I didn’t feel like I was in danger. But how would you react?