Sometimes that person will walk into Lush as you are picking up Jasmine & Henna Fluff and you will hide behind the nearest fixture.
I had replied to the person's status saying places like Hobby Lobby are being discriminated against by not being allowed to control what female employees talk to their doctors about. It turned into two people calling Plan B "the abortion pill" and me using science to point out that it is not that and explaining what Plan B actually does.
The best part was when I simply said that Plan B doesn't cause an abortion and I got a response saying "says who" and I replied "Science."
Hence my hiding when I saw the person IRL.