What is a polygon with four sides called?

What does GOP, the nickname of the Republican Party, stand for? France's political and social system before 1789 is known as the "ancien" what? What is a political subdivision of Switzerland called? Which politician was nicknamed "Tail Gunner Joe"? A popular 1889 John Philip Sousa march was commissioned for an awards ceremony held by which newspaper? A popular 1940s style of ankle socks shares its name with a nickname for Robert. What are they called? Which popular 1960s hairdo shares its name with an insect's home? Which popular 1990s sitcom starred Jerry as himself?