Make a cup of very strong coffee - use 100ml of water and 6 full heaps of coffee. Make it as strong as possible! Wait until it cools down. 

Once the coffee is at least lukewarm (I know how hard it is to wait for this heavenly deliciousness to be ready!), add the rest of the ingredients. Mix well. 

Pour into a bottle & keep in the fridge. It probably won't last that long but you can keep it in the fridge for as long as a month.