As a foreigner in China, you will probably attract lots of attention from the locals. Many people like to take photos and videos of me without asking so this is how I get back at them 😂.
If I catch them taking a photo of me, I whip out my phone and do the same thing to them to give them a taste of their own medicine. I find it hilarious seeing the look on their face when I catch them hahahha.
It is necessary to come up with responses like this or else you are the one feeling awkward and gawked at. Other times I will just turn away but it still feels like you are being intruded on. This is the best course of action imo.