Now that's a fantastic use of the back of a 50p -- explaining the odd sports rule like offside. The Royal Mint has been putting its collection of commemorative 50p coins into circulation since 2010, but now you can buy the complete set of the shiny 29 sporting 50p pieces for £85 or £2.99 each (plus postage).
The football coin is the only one with a rule embossed on the back of it, but the other 28 feature iconographies of olympic sports designed by competition winners picked from nearly 30,000 entries by the Royal Mint. The 29 coins highlight 29 separate sports, including archery, badminton, boxing, cycling and fencing, and many others including some disabled sports like boccia.
Considering they've been in circulation since 2010, I'm surprised I haven't seen any. Still, now I know they're out there, it's time to start a collection. Have any of our eagle-eyed readers spotted one while rummaging in your wallets? [Royal Mint via Yahoo! Sports]