Mix up the caffeine drink with the schnaps to create a mixture with an alcohol content, low enough to enable freezing. In my case the schnaps contains 22% alcohol. This compares to 33% for original Jagermeister. By mixing 2 parts Red Bull with 1 part of the 22% schnaps, the final liquid will contain just over 7% alcohol. As pure alcohol freezes at -114 degrees Centigrade and water freezes at 0 degrees Centigrade, the new mixture should freeze at 7% x -114C = just under -8 degrees Centigrade.
Enough 'science', let's mix it up and fill the ice lolly moulds!