""My favourite is when you buy something, take it back and the assistant tells you it is in the sale now and will only refund you the sale price. Duh!""
this is illegal... if you have a receipt and are within 28 days (its actually possible to go beyond that, but hey...) then they HAVE to refund original retail price. i've been there MANY times... its the law.
ALSO, A NICE LITTLE TRICK TO CASH IN ON THE CASHIERS WHO ARE TOO USED TO PLASTIC... this only works normally around xmas time. if you buy something for, say, £35... count the money out in front of them... literally speaking the amount you lay down (or even better, in their hand)... count the first tenner as a 'twenty', then the next tenner as ten (lay it down quick)... then unload coins on top. the subliminal messages you send by speaking a fake total, PLUS all the shrapnel genuinely confuse them into getting away with it. NO LIE: THIS WORKS ABOUT 80% OF THE TIME EVERY XMAS/NEW YEAR. (better with a queue.) try it... whats the worst that can happen? just plead genuine mistake. (also works with any divible involving coins... palming a 10 off as a 20 is pretty easy) this is why i rarely reach for plastic...