Came across this simple, interesting promotion in a packet of Little Hearts biscuits! So you open the packet and there is a small heart shaped piece of paper with a plasticy centre. You place your finger in the plasticy section and after some time it changes colour. On the paper edges, you have the meaning of each of the 4 colours... are you full of heart, hmm so so or Keep distance!

It kept a whole bunch of mature adults in my office busy for some time! And so - even though it showed I had a black heart - its kind of sweet!