I ran into a Nestle produce overseas that was pretty cool. Versions were Hot Chocolate and several varieties of coffee.

It's a product in a can. You push down some tabs on the top of the can, then turn it over. IT HEATS itself. After the recommended amount of time, you open it up and you've got a hot drink.

I got a half dozen of these to bring home, then thought for a moment about something that heats when you turn it upside down... on an airplane... after (pobably) having NOT gone through security at a Middle Eastern airport. Wish I had some of those just because they were so unusual.

edit:
NOT Nestle, and available at Walmart! [Link: walmart.com]