With an iphone you can turn off the flash and turn off the volume.
I once had a thread here about catching other guys taking pictures of women. These days it’s probably pretty common, but I don’t know every law about taking unauthorized pictures, and remember that at public places like McDonalds there’s a good chance of a security camera catching you.
A kid that worked at the local public pool told me that someone once reported a man taking pictures of the girls in bathing suits outside on the pool grounds, and they called the cops on him. He was being creepy, but I wouldn’t have thought what he was doing was illegal. Apparently it was.
I’ve generally found that if I take/obtain a picture of an attractive woman that I don’t know that pretty quickly it will be something that I lose interest in and not worth the hassle or worry of hiding it. If it’s someone I know it’s a different story.
But if it's something irresistible and extraordinary, then it should be posted here