Looks like a regular vacuum flask. However, there is no insulation; instead, the base of the flask is made of refractory ceramic, holding a small but useful quantity of thermite.
A friction igniter triggers the thermite reaction, and the heat rises into the drink container, rapidly raising its temperature
to boiling point or beyond.
The unit is-re-useable; just clip on a new thermite pack.
Guaranteed to break the ice at parties.
May cause death or serious injury if used correctly.