I picture Karen as a mommy with short, colored hair (in the let-me-speak-to-the-manager style). She drives a big SUV of the highest trim level. She has a degree, but is a stay-at-home mom. She sent her kids back to school anyway for some "me time". The kids play soccer or lacrosse. She does Pilates. She has a spoiled rotten labradoodle. They have a lake house. Maybe, they have a pool as well. They keep an expensive boat in storage at a marina and use it twice a year. They have two precious children who can do no wrong. The husband wears collared shirts anytime he goes outside. He has Salt Life sticker in the back window of his King Ranch pickup but he never fishes. Nobody knows much about him because he's always too busy supporting the lifestyle to enjoy it. If he ever loses his earning potential, Karen will decide they were just holding it together for the kids.
Of course, I'm stereotyping upper middle to lower upper class white people. How'd I do? This description fits a good many people I've known through the years. Actually, most people have some Karen in them. It's an overwhelming desire to not be pushed around. Squeaky wheel gets the grease. Most of our wives have more of it than we do.