So I asked for $50 cash back at the grocery store, and I thought I saw the lady hand me two 20s and a 10, so I just stuff them in my pocket with my receipt and left with my groceries. It wasn't until later when I tried to buy dinner at Arby's with what I thought was a $20 bill (Yeah, bad habit of mine: going out to eat after buying a ton of groceries) did I discover that I was holding a $10 bill in my hand.
The grocery store shorted me 10 bucks!
I've been muttering every obscenity I know for the last 15 minutes, but it hasn't made me feel any better.