Some more of my favourite open zipper stories
During my last years of school (2001-2004), there was a girl who hated math classes as much as I did and I remember that at least one time (probably more like 2 or 3 times) she went to the bathroom before a math exam and returned with her zipper completely open

And she was very sexy, curvy, big boobs, wearing tight jeans

I guess she was so nervous because of the exam that she forgot to zip up hehe. And I still remember that the same thing happened one time to another girl from the same math class.
Another nice open zipper story which probably happened around the year 2003 too took place at the reception of a doctor's office, the receptionist was a lady probably in her 50s and she was wearing some comfortable light summer pants/trousers. And these pants/trousers had a very long zipper which happened to be completely open, when she sat down it was gaping open and her underwear was completely visible
A bit more recent story which happened about 5 years ago is that I was with a group of about 20 people for the majority of the day and when I happened to walk past a girl/young woman who also belonged to the group I noticed that the zipper on her jeans was completely open. She noticed me looking and discovered the wardrobe malfunction and zipped up. But the best part was that every time I walked past her again, her zipper was completely open again and she noticed me looking again and zipped up again. Apparently, her zipper was broken and always unzipped by itself, I enjoyed this so much

And she also happened to be the kind of girl I like, slighty chubby with a little sexy belly and a cute face