With special Mars and Snicker wrappers you can win a free one. In this last week I have bought 1 and with each free one, have won another. 4 in one week. A work colleague has won 3 so far. There must be plenty of them about which is amzing for a change. Trouble is, Im putting on weight :>)
Oh god, I've been on a bit of a Mars addiction recently (almost one every day) but I never look at the wrappers. Imagine how many free Mars Bars I've probably thrown in the bin! :(