Just had my own "Karen" encounter in grocery store because I was trying to help someone
I saw a woman and child outside a store and went to give them some $ then asked if I could get them anything from inside. The woman answered, "milk?" So, I asked them to come inside with me and get what they needed. I expected to spend $200 or so, because that's about what it costs to fill your cart. We are inside, she keeps asking if things are okay, milk, eggs, bread, butter, all basics.
About this time a woman comes up and asks if she can "show me something over here," and she takes me aside and warms me about scammers. Yeah, lady, I know, I can tell if someone is a scammer, and, I told her, "They are not scamming, I offered." Well, she can't quite take that, so she proceeds to take a photo of me and the woman (I don't 'recall giving her permission so hope she doesn't post it, LOL), but she is on a tear now and gosh darn it, going to do something about it! The horror. A woman buying groceries for another woman with a small child.
She took time to tell the store clerk all about it, and how awful, and you should chase these people away from your store. The poor woman I'm helping was so sad. Her English was pretty good but not great, so it broke my heart a little to go from such a joyful state to now sad, because someone just cannot stand the thought of helping another. I told the clerk that the lady was wrong and I had offered, so no scam going on here. So that's my story, and I won't stop helping when I can.
= new reply since forum marked as read
I think a large majority of normal people with a heart would have praised Lettuce’s kindness and generosity.
And perhaps would have helped fill her cart by purchasing some necessities themselves.
Good on Lettuce Be for standing up to this mean, bitter and nosy person.
And that would be to loudly proclaim to Karen (so everyone could hear):
What is YOUR problem?
Are you trying to rob me?
ETA:
Thank you so much for your kindness. You make the world a better place. 
You did good. 
You’re giving them business, and it’s very kind of you. 
Way to go! 
People aren’t just cruel to others; they hate it when they see people being kind to one another. As if it’s the kindness and not the cruelty that’s the problem.
Thank you for your kindness.
Its the way to go, and you are a shining example of it.
I told my kids, if they are scammers it's on them. You followed your instincts and did the right thing.
We all need some!
You did my heart good!
thank you.
never let assholes deter you from doing what you know is the right, humane thing.
Some people are so broken inside that they can't show kindness to anyone. In Karen's case she wanted to take that joy from you, too. I paid for groceries once when the person in front of me forgot their wallet. The lady behind me told me I shouldn't do that because some people do that to get out of paying. I said, "Well, I believe the Good Book tells us to do good whenever we can, and it is my honor to help my neighbor! The cashier replied, "Amen," and the lady behind me shut up. I continue to pay when someone doesn't have enough money, and I applaud your choice to do so, too. We're all in this together!
