I was just out of high school, maybe 19 years old, when I found a Personal Digital Assistant, or PDA (this was back when those were a thing, remember those? Look it up kids) at the convenience store I worked at. Policy was that if something valuable was left there, and no one came looking for it, the person who found it got to keep it (if they wanted it). It was a pretty nice one as far as I remember, and in good shape. But I didn't really have any use for it.
I took the PDA to the mall one day to find out how much it was worth from someone at a cellular kiosk or something and was told it retailed for $200 but I could probably get $100 for it since it was used and I didn't have any boxes or chargers or anything that would have come with it.
Walking through the mall that day I decided to stop in to Suncoast Video (again, this was back when those were a thing, remember those?) to say hi to a buddy of mine who worked there. He wasn't there, but there was this girl that also worked there who had always been very flirtatious with me. Nice enough girl, but I just had no desire to rescind that flirtatiousness and actually tried hard to avoid interacting with her. After asking her if my friend was there and being told no, she asked what I was up to at the mall that day. I told her about the PDA and that I was looking to sell it. She mentioned that she was looking to buy one and asked what I wanted for it. Sizing up the situation, I realized she was probably only asking me because she liked me. So I told her I wanted $200 for it. She told me that she'd buy it for that (cha-ching) and that she'd go to an ATM on her break. All I had to do was wait around for an hour or so.
I killed some time at Waldenbooks (this was back when...you get the point) reading comics and ogling the Playboy covers, then met up with the girl at the predetermined time and place. After getting the money from her and giving her the PDA, she asked if I wanted to get a slice at Sbarro's with her. I said no, I had stuff to do and that I had to get going, but maybe some other time. I don't think I ever actually spoke to her again.
TL;DR Took advantage of a girl's crush on me to sell her a PDA for way more than it was worth.