It seems that at least in a few states in the US suing a bar over 'ladies night' isn't stupid. I doubt that anyone was awarded $$$ for damages though.
You are correct, comparing " macdonald's fat suit to charging different prices based on sex, " is ridiculous, typical mixing of " apples and oranges".
and yes, men have been awarded damages, in California, everytime a business denies equal accomodation based on sex, they have to pay $5,000 dollars or more in damages, dependiong on how stupid the bar/club got with the patron. 