Mama Tee Series -Fake Currency Brouhaha

I had an embarrassing experience with fake currency sometime last week. I had bought some groceries in a store, gave the sales girl some #1000 notes and a #500 note. After counting the money, she examined them one after the other and then called on another staff, a guy to come check something. She handed him the #500 note. The guy checked it and asked me to change it that it was a via IFTTT