Every time someone questioned if I had a mask I just told them I had a medical condition. Most people just let that slide.

Then I was walking by and this Karen (blonde short haircut, older middle-aged woman), point to her mask and says "it's a requirement you wear a mask". I said to her my usual "I have a medical condition and can't wear a mask." She immediately says "no you don't have a medical condition!" I tell her that I did and that it wasn't her business anyway. She starts saying something about this is a pandemic and it's my responsibility to wear a mask and that I'm ruining things for everyone else. She pulled out her phone and started recording me around the store. I met up with my friend and then she hung back and just recorded at a distance.