WTF!? No fair!
Something sort of like that happened to me a couple of years ago. I went to buy some ice cream, from those mexican dude who push around ice cream carts. Anyways, I gave him a $10, for something that costed like $4 something and he gave me back like around $20. lululul.
But I went back, and told him, and hoped he might let me keep a dollar or something for helping him, but he corrected it and the next person in line went to order. Damn it. He’s going back to Mexico… (no offense)