I can test negative, put on a mask go to the grocery store, come in contact with someone who is not wearing a mask and have a false sense of security that I'm still protected and negative.
To hear someone say I tested negative this morning should be followed with did you wear a mask when in contact with anyone and did they wear a mask? This is a serious topic, but I have to add something humorous to break the negativity. The South Park Pandemic Special is hilarious. We must be mindful but keep a positive outlook.