Imagine a compact, battery-operated peltier system in the shape of a pen (or rather marker), and make it either heat or cool your drink.
Now, I'm aware that computer-geared peliter systems can take off several degrees of heat rather effectively on one side, and in turn heat it's other side.
Now
with the flip of a switch, soak a few degrees out of that scalding cauldron of coffee, or rejuvinate that luke-warm glass of cola.
Extra-capacity heat exchangers can be sold as add-ons to either side of the device. Equip the heating-side with the shape of the Chernobyl plant, or a tiny model of Three Mile Island. Respectively, a penguin or ice berg can adorn the cooling side of the system as not to get them confused.