"Jerry cans" are so-named because they were originally designed and stockpiled for the German Wehrmacht during the build-up to WWII. Originally they were called: Wehrmachtskanister.
(Jerry being a disparaging wartime name for Germany and Germans)
A Jerry Can has the following (user) design aspects:
+ They can be stacked with little wasted space;
+ Their three handles allow easy carrying by either one or two people;
+ The handle design also allows for two empty cans to be carried in each hand.
+ The small built-in air space allows for expansion while minimizing condensation, and ensures that they'll float even when full;
+ The US version of the jerrycan is covered by military specification MIL-C-1283;
+ The sides of the can are marked with cross-like indentations that strengthen the can while allowing the contents to expand, as did do air pockets under the handles if the can is filled correctly.
+ It uses a cam lever release mechanism with a short spout secured with a snap closure and an air-pipe to the air pocket which enables smooth pouring (which is omitted in some copies).
+ Typically, the following NATO color coding is used:
For more info: http://en.wikipedia.org/wiki/Jerrycan