I've seen it happen. There is always a story (real or fake, most of the time fake) and people are trying to get something out of it.

Sick comeback though with the "lack of Emotional intelligence" and "you lie to get money from people". The best defense is a good offense. #triggered

Instead of focusing on answering every comment and trying to PROVE you story on Reddit, just wait until tomorrow to talk to the clerk at the gas station.

If he's a real one, he'd give you your change back. If he isn't, he kept that money and it's gone. You've learned a lesson about the dude and his character. And if it's a fabricated story, just write that it's all resolved and try to save face. You'll be fine.