Very surprised that chocolate can make fire, but .......
For making fire with can coke and a chocolate bar first one is forced to be a sunny day. OK ?
Then we need more of the chocolat and coke, a newspaper or very dry grass.
First hold on the can and a piece of chocolate and rub the bottom of the can with the chocolate.
rub with a cloth until the bottom side of a can is very well polished.
The next step will focus it in the sun and reflect the sunlight on the newspaper or the dry grass.
Wait for a a while and the fire will burning.
Good barbecue.