STEP1 - When you’re out and about collect up some copper coins. The older and dirtier the better.
STEP2-Pour out a glass of your cola.
STEP3-Cover one side of each coin with Blu-Tac but leave the other side open.
STEP4-Pop your coins into your glass of co*ke.
STEP5 - Sit back and wait but you should be able to see a difference in the colour of your coins within about an hour.