First of all you need to go and look in the trolleys for any discarded shopping lists. I miss those threads.
Then, nonchlantly, possibly whistling, you must saunter around the back of the supermarket. Locate the big green bins and quickly, with bags ready (bags for life of course), you must rummage around and fish out any food you spot. Stuff it into your bags and hightail it away.
If you are accosted, you must explain that you're only doing what the BBC wants you to do. Then come back home, log onto mumsnet and let us know what you found an what you're going to cook.
I shall be in charge and I shall be awarding points based on the supermarket, the produce collected, whether you actually entered the bin and how you dealt with any supermarket employees.
Good luck!