I can go about with my zippered things undone to some extent, though having bits of my clothing waving around can get VERY annoying VERY quickly. It is usually only for hot weather that I do that anyway.
As for having the zipper all the way up, it depends on my mood. I'm more psychologically comfortable with the zipper done up to the top (I don't like my neck showing) but I'm more physically comfortable with it undone down to my collar-bone (so that revolting man-lump on my neck isn't being painfully constricted).
I tend to alternate depending on my mood and / or surrounding temperature.
tharn wrote:
It's even part of a larger rule. You NEVER button or zip all the way up to the top unless you're wearing a tie. The top button on a dress shirt is called the "idiot button" because only idiots button it. In Basic Training, I made the mistake of buttoning the idiot button on my field jacket. I was asked, "Why the @#$# is your idiot button buttoned?!" The answer was, of course... "Because I'm an idiot, sir!"

I swear... except for my work shirt, I will tend to play bizarre games with buttoned shirts. Like sometimes I'll have them all buttoned up, other times ALL unbuttoned (including the cuffs of the sleeves). Sometimes I'll do up every other button... or leave one or two open at the top and bottom.
On at least one occasion the ONLY button I had done up was your so-called "idiot button".... just for the sake of being different. I went around with the rest of the shirt draping open, but clasped quite tightly around my neck.
Just the way I am, I guess.