This is going to sound ridiculous, but at the time it was the most devastating thing that happened to me.
When i was around 9 I used to play that online game called Animal Jam. Of course, just like every cool kid out there ya boi had a membership. With this membership i was able to obtain the premium currency, Diamonds, Quite easily. With these Diamonds i went the the Diamond store and bought an expensive item called a Spike Collar. I have zero clue why these were the most sought after, but everyone always wanted one of the authentic ones. I had two authentic ones and one store-bought one at this point, and i wanted another authentic one. So i went to the main area and started advertising the crap out of my incredible offer for an authentic one. Some dude comes up to me and says „I dont have a spiked collar, but i have something even more rare.“ naturally, i am intrigued. I ask him to show me and he shows me these Ram Horns that look hella cool. Of course im skeptical so i ask him if he is sure these will outmatch the value of an authentic spiked collar. He says yes, they will, and that in exchange he wants one of my authentic spiked collars. This sounds like an excellent deal to me because he says that these horns were extremely rare and a beta item. Beta items are hard to come by because only a few of them ever existed. A beta item could easily outpace 5 spiked collars. So of course im in and we initiate the trade. Just to be nice i toss in a few less rare items and accept the trade. Once we finish the trade, this dude starts laughing. Immediately, i know somethings up. He says „check the store“ and leaves the lobby. I looked at the store. There, in the store for like 5 of the non-premium currency, are the ram horns. I got swindled out of one of the most sought after items, and you bet i was pissed. The problem is, i never got the guys username so i could never report him for scamming me. I am 15 now and i still haven’t forgiven him.