Sheldon Cooper isn't the only one who can have fun with flags. With the help of the Central Intelligence Agency's World Factbook Flags of the World site, you can too!
The site shows dozens of national flags and gives a brief description of each, which often includes information about the history or meaning of the design. For instance, in Afghanistan's flag "black signifies the past, red is for the blood shed for independence, and green can represent either hope for the future, agricultural prosperity, or Islam." So, it really isn't easy being green. In any case, read all about these flags and see which ones make you salute.