I was a bank teller in college and I'd probably see a fake $100 or $20 at least once a week. It got really, really easy to tell after about 3-4 months of handli

I was a bank teller in college and I'd probably see a fake $100 or $20 at least once a week. It got really, really easy to tell after about 3-4 months of handling tens of thousands of dollars a day (I deleted it long ago, but I at one point had a photo of me juggling three $100,000 bricks of $100 dollar bills, incredibly stupid thing to take a picture of while at work in the vault, but I was 19 and didn't know any better). 9/10 times the counterfeit bill owner had no idea as they were mostly in cash deposits from local restaurants and whatnot. But 1/10 you could tell the person was trying to pull a fast one. I never made a big deal out of it, just let the customer know it was policy to confiscate, I'd file a report and give them a receipt letting them know I was sending it to the authorities. They could take it up with them at that point.