Milka appear to be superstars when it comes to creative sampling:
Source: http://www.promosapiens.be/index.php/sampling-milka/
In the following promo, strangers must hold hands to connect the cow to the machine in order for chocolate bars to dispense:
Source: http://www.psfk.com/2013/09/milka-hand-holding-vending-machine.html, http://www.brandingmagazine.com/2013/09/09/hold-a-hand-receive-a-milka-bar/
And here is an adorable Milka commercial that plays on the purple cow theme: