Whenever someone I know goes abroad, it's almost certain that they'll bring back something awesome penguin trinkets as souvenirs. And indeed, when Petja and Tiina went to London for their anniversary earlier this year, they brought some hot chicks with them. No, really.
This is Hot Chicks Hand Warmer, from NPW. This type of heat pad is generally called 'crystallisation-type hand warmer'; They generate heat through the exothermic crystallisation of supersaturated solutions and are re-usable. What this amounts to is that this penguin contains a plastic bag filled with sodium acetate and inside that there's a metal chip. Bending the chip initiates a reaction, which in turn generates heat. To 'recharge' the warmer, all you have to do is to sink the bag – sans penguin – into hot water until the contents are fluid again.