Step 1: First.....
First off this instructable is for educational purposes only.
So first find a coke machine or a drink machine that sells coke.Make sure no-one is around.
Step 2: The Keys
The keys for this step are:In this order 4,2,3,1 and then a menu pops up.they can say different things according to the machine.But most of them have four menus:cash,sale,rtn(return) and menu.Now to change the menus around push the second or third button and to get out of the menu go to rtn(return) and push the four buttons.