What are those pins some US polticians wear?

Question

not the flag pins...but the ones that look like its some sort of fraternity pin or something? I am sure there are different ones. can you mention what some of these are?

Answer 1

Members of congress are give a pin that allows them to enter the capitol building without going through the metal detector

Answer 2

The characters from "Spongebob Squarepants" (it's only logical).

Answer 3

You may be referring to the House of Congress members lapel pin. I assume the Senate have their own too. The second link has a picture of the pin.