Jason went as the Joker as the nurse (played by Heath Ledger).
I was the Anarchy Cheerleader from Nirvana's 1991 breakout video "Smells Like Teen Spirit".
wiki - the video featured the band playing at a pep rally in a high school gym to an audience of apathetic students on bleachers, and cheerleaders wearing black dresses with the Circle-A anarchist symbol. The video ends with the assembled students destroying the set and the band's gear.
Black pom-poms not shown.
See the video HERE. You forgot how good it is.
J stayed in character all night adding to his completely creepy get up.