Had a flight a few months ago, and had my first in person Karen experience.
Was in a small regional hopper plane to a bigger airport, it only seats about 80 people and the overhead bins are about 1/2 the size of a standard overhead. Karen brought her suitcase that looked like it barely would've fit in the regular sized overhead bin on the plane and it very obviously wouldn't fit. One of the ladies in the seat near her mentions that she'll have to put a tag on it and have them do an à la carte checked bag.
In case you've never used an airline that has this service, it's basically a free checked bag that you get to drop off/pick up at the jetway. It's pretty awesome, especially when you're going from a small airport to one much bigger like LAX so you don't have to mess with baggage claim and lost/stolen luggage.
Anyway, she gave the snappiest most sneering "No! I'm not letting them take my bag!" I've ever heard to the woman. I don't know how all Karens manage to look and sound the same, but they have to be made in a factory to be so uniform. She made enough of a fuss that she eventually convinced the poor flight attendant babysitting her to buckle her suitcase into one of the empty seats up in first class.
TL;DR~ Karen does Karen things and her suitcase gets a better seat in the plane than me for free.