Submitted by rauschejuler t3_11yr2b3 in tifu
This happened in the early 2000s when I was about 17. I come from a very small and rather poor town where it was nothing out of the usual to give away your used clothing to family and neighbors, for children this also extended to socks and underwear. I remember that I always got my cousins underpants when she outgrew them until I was at least 12. So when I was older I went to sell my used clothing on a flea market and took some bras and (obviously perfectly clean) panties I grew out of to put in a "free to take" Box under the table.
Due to my age and upbringing I had absolutely NO clue that panty sniffing was a thing.
A elder gentleman approached the table and asked me about the panties. I very eagerly told him that yes, I wore them myself and my age and so on. In my innocent mind I thought he wanted them for his grandchildren and was asking about my age to measure the sizing. He then proceeded to actually sniff them which I took as a measure of cleanliness. He asked if he could take all of them and went off with the whole box. Even though I found him very weird and didn't like the interaction with him I was very proud of myself and happy that I did such a good deed. It took years for me to realize that I supplied a pervy older guy with a huge supply of worn adolescent panties.
TL;DR: I gave a whole box of clean, but worn underwear to a guy without realizing what he'd probably do with it since I had no idea about panty sniffing.