Just last week I had one of the "I can bring whatever size bag I damn well please on board" women on an ATL-EWR CO flight. A much more frequent flier than her was kind enough to loudly point out to the bag lady that "that's an argument you're not going to win" when the FA called her out on the size of the bag, which (no exaggeration) had to be double the carryon size limit. FA made her repack the bag and break it into two bags. Upon landing, who is the one person going against the flow of traffic to pick up her crap from the last overhead bin on the plane? Yup.