Physicists at the University of Hertfordshire have been celebrating the festive season with Tia Maria and cream. They used the combination to create the illusion of a planetary storm for an educational video they made for sixth-formers.
Apparently, if you cover a glass of Tia Maria with a layer of cream, you get long-lasting convection currents from the evaporation of the alcohol. And if the system stalls, taking a sip of the Tia Maria with a straw is all that is needed to start the currents flowing again.