"I would say I'm sorry I missed last week, but I'm not," John said bluntly as everyone arrived. "I went to get supplies for class, and got sidetracked making some bets." He pulled a fistful of bills out of his pocket and tossed it all on his desk. "But now we have decent counterfeit cash for you delinquents to play with."

Was it an Honesty Day? Honestly, Constantine wouldn't even fucking notice.

"You're all broke students, so you'll like this one," he continued. "Change raising, also known as a quick-change artist, is a common short con and involves an offer to change an amount of money with someone, while at the same time taking change or bills back and forth to confuse the person as to how much money is actually being changed. The most common form, 'the Short Count', has been featured prominently in several movies about grifting, notably Nueve Reinas, The Grifters, Criminal, and Paper Moon." Yes, John watched movies. What else was there to do around here?

"For example, a con artist shopping at a gas station pays for a cheap item - under a dollar, say, for you Americans - and gives the clerk a ten dollar bill. The con gets back nine ones and the change then tells the clerk he has a one and will exchange ten ones for a ten. Now, here's the con: get the clerk to hand over the $10 before handing over the ones. Then the con hands over nine ones and the $10. The clerk will assume a mistake and offer to swap the ten for a one. Then the con will probably just say: "Here's another one, give me a $20 and we're even." Notice that the con just swapped $10 for $20. The $10 was the store's money, not the scammer's."

"Now, say you're the clerk. To avoid this con, keep each transaction separate and never ever permit the customer to handle the original ten before handing over the ten ones. It's just common sense."

"Another variation is to flash a $20 bill to the clerk, then ask for something behind the counter. When the clerk turns away, the con artist can swap the bill he is holding to a lesser bill. The clerk might then make change for the larger bill, without noticing it has been swapped. The technique works better when bills are the same colour at a glance like, for instance, American money. It doesn't work so well in places where a ten is pink and a twenty blue, and so on, unless you've scooped your mark in advance and know he's colorblind."

"A similar technique exists when a con comes to a gas station with a young clerk, buying something cheap, showing him an uncommonly huge bill while not giving it and telling the clerk to prepare the change. While he's busy counting the change, the con would ask many questions in order to disturb the young clerk. When change is counted and ready the con is acting as if he had given the huge bill. If the clerk does not remember having received the bill, the con will say he gave him the money. If the clerk is weak or disturbed enough, he could let the scammer go away with the change."

"Now here's your money." John started pulling even more counterfeit money out of his pockets, tossing random handfuls on their desks. "See if you can scam each other, and keep a hold of your own money at the same time."