Cash For Granny
Biting The Note, The Flu
Shop owners, post offices
The Con artist walks into a post office and buys a small envelope and a stamp. He talks to the person behind the counter about his sick aunt, and how he is sending the £20 to help her out. Problem is he only has the £20 in change. He doesn't want to send change and asks if the she can exchange the coins for the a note.
As the change is being counted, and con artist places the money in the envelope and seals it shut. It is then revealed that he only had £19 in change, and is pound short. The embarrassed coin man apologies and says he has come change in the car, he grabs his £19 in change and leaves the sealed envelope behind. Saying he'll be back soon.
He doesn't come back
This scam invokes a bit of acting and a quick piece of sleight of hand. Obviously the aunt is all an act. Instead of placing the £20 note in the envelope, The con artist initiates the action of placing it in the envelope while actually sliding it done the side instead. The envelope is then licked shut and the note palmed away.
The Con man leaves with £19 in change and the original £20.
How to avoid being scammed
A good practise for all retail establishments, is to not hand out goods/cash until you have counted the money. Seems simple, but many scams count on you not being 100% vigilant.