Produced by the German company Trekking Mahlzeiten as a snack for those on the move"Trek 'n Eat," the German-language site proclaimsthese slim pop-top tins are labeled simply "Cheeseburger" and feature a pair of canoes pulled up to the shore of a forest-rimmed lake. These burgers aren't intended to be grilled over a campfire, however. Instead, you heat up the cans in boiling water.