While some of the techniques laid out in "Tricks of Short Change Artists," from the Oct, 1930 issue of Modern Mechanix may have shifted over the years, the principles remain largely unchanged. I could read about con artists all day long -- I've only been conned once (that I know about), but I still reel with the knowledge that someone managed to pull off a trick that combined conjuring, social engineering, and connivery to separate me from a small-to-mid-sized wad of cash.
Organized short-changing of filling station attendants is becoming common and it is evident that there are a great many artists engaged in this branch of the business. The tricks are many and varied. One favorite is to offer a twenty in payment of a bill. On getting the change, the stranger will count it over and discover that five or ten dollars are missing. The method is to fold over the five or ten and hold it between two fingers underneath another large bill in one hand, while asking the station attendant to count the change in the other hand. This trick has been the means of cheating a great many oil station men. The loss is # seldom discovered until check-up time at night.
Another method of making change appear "short" a bill of any denomination is the use of a clever sleeve attachment. It is merely an elastic running up the coat sleeve; at the end is a spring paper-fastener. The con man merely sends one bill from his change up his sleeve, and the dealer can, of course, see no method of accounting for the loss excepting the most obvious one. that he has made a mistake!