Do I KNOW you?

Why is it that some strangers think it's okay to run up to pregnant women they DON'T KNOW and rub their tummies? Honestly, having been pregnant four times and the last thing I want is for some person I don't know pawing at me! It bugged me so much! And what got me even more was if I were to swat their hands away or whatever, THEY had the nerve to be offended! Are you kidding me? Yup... People suck.