But why does the expression entail insulting military men and women, and their families? What have they ever done to the NFL?
It has to do with workplace rules. For example: it's ‘legal’ to sing ‘Happy Birthday’... But if YOU insist on singing ‘Happy Birthday’ to every client - every day - in spite of your boss telling you to stop because it's costing business, - you'll get fired.
YOU still have the right to sing ‘Happy Birthday’ - but on your own time. This is the same.