A guy looked at me in the bathroom, what should I have said You know those situations where you think back on the situation and wish you would have said something different? Here is one of those.

Situation

I am a male in my lower 20's and I was using the urinal at an airport in China. It was an odd hour of the day and the bathroom was empty. A minute later a Chinese man, 40'ish years old, comes in and chooses the urinal beside me. If you are a male you know this is against the bro code...

While doing our thing the other guy peers over the divider at my 下面的 (private parts) and looks at me and smiles.

I was so taken aback that I froze and couldn't say anything, not to mention my Chinese was not that good at the time. I was also shocked and a little angry.

Question

What would be appropriate to say in this situation? I was pretty angry at the time.

Thoughts

I feel like I would have said something like:

你干看着什么啦？！
你是农村人吗？
天啊。

Does those sentences make sense in that situation? What is an appropriate response in Chinese?
I don't think there is any "appropriate" response for the old guy since his behavior is abnormal. But you can think about it if it happens in your hometown and how would you react or say in English? Maybe some curse words or yelling.