XYZ which stands for eXamine Your Zipper - a coy way of warning that the barn door is open and the stallion's running free, or, to put it more prosaically, your fly is open. Now this, frankly, is the sort of thing I want to be told, by anyone, as soon as it's noticed. Do I have spinach on my teeth? Has my deoderant failed me? Is there toilet paper stuck to my shoe? Please, please, tell me right away. Don't let me wander around with my hem tucked into my pantyhose while the general public laughs and mocks me.
Assuming that other people would rather not flash in ignorance, I am quite unembarassed to walk up to total strangers and say, "Your blouse might have some slippery buttons. Did you mean to show that much?" Or, "Sir, your fly is open." I also offer mints to people with bad breath.
So what is the other side of this? Would you rather not know? Would you prefer that I politely ignore that shred of jerkey stuck between your teeth and waving at me each time you laugh? Should I try to find a more tactful way of saying, "You have baby puke all down your back."