Hats off is an expression of admiration for someone who has done something praiseworthy. Hats off to you is a sign of respect or congratulations. Hats off to Roger and Ms. Nesbitt for all of their hard work for keeping this alive.!!!!
There was a time in history when a mans wardrobe included a stovepipe hat and meant you were a member of the upper class, it was customary to briefly remove the hat as a sign of respect. Even though men's wardrobes have changed sometimes you still still a man tip his baseball hat in a game to show respect to the opposing team.
I was driving past a street the other day that had had quite a bit of construction done and I noticed these poles with top hats on - the caps look like hats to me.