That is shocking, and shouldn't be done. The same goes for people that dress for 2 climates at the same time. 4 layers on top, 1 on the bottom and thongs.
I would politely ask, "what gave you the idea of combining your pub shirt with your formal wear"? They'll be able to put two and two together.
A large Islander woman stopped me in the street recently, and said, "Only losers still wear Onitsuka Tigers. This isn't 2008". That was a difficult situation for me to handle.