Earlier this year, I met in town with a friend (who knows about my open zipper fetish and doesn't mind if I leave my zipper open hehe). I was wearing an old pair of jeans with a broken zipper which always unzipped itself after having been closed. And these old jeans are rather tight so due to the pressure on the zipper it always was completely open again after a few minutes hehe. I spent all the time (several hours) like that (I had tucked my t-shirt into the jeans so that the zipper was well visible). We were at some well populated/crowded places in the city centre and judging by the looks a lot of girls and women (and some guys too hehe) noticed my open zipper, no one told me though ^^ I hope I can do this again soon, it was such a rush knowing that my zipper was completely open and many girls/women noticing it and looking
Apart from special actions like this one, I regularly leave my zipper completely open on public transport on my way to work and back home, last time I did it a girl noticed and told her friend who then took a look at my zipper too and they giggled during some minutes hehe
