Countries that do not have a rectangular flag are Nepal, Switzerland and Vatican City. These flags are square, save Nepal's. It is a double pennon, or a flag in the shape of two triangles.
The Nepalese flag is bright red, which represents the color of the rhododendron, the national flower. The color also represents the fortitude of the Nepalese people. The top pennon shows the crescent moon and the lower shows the sun. The flag's border is blue, which symbolizes peace. Some also believe that the two pennons symbolize the two great religious of the country, which are Hinduism and Buddhism. They might also represent the peaks of the Himalayas, where Nepal is located.
The flag of Switzerland is square and features a white cross on a red background. It symbolizes honor, freedom and fidelity. It's been the national flag since 1889 and was modeled after a flag of Schwyz, one of the country's oldest cantons.
Vatican City is one of the smallest countries in the world and is ruled by the Pope. Its square flag was adopted in 1929 and has a bright yellow half and a white half. The yellow half is empty, but the white half holds the gold and silver keys of St. Peter and the papal tiara.