Well I'm from New Orleans and AOII had a Mardi Gras swap a few years ago.
1. Mardi Gras Masks
2. Mardi Gras colors are purple, green & gold
3. Umbrellas to "second line" around the room
4. Good Jazz Music
5. Mardi Gras Beads
6. King Cakes to eat (Randazzo's has the best, website below)
You could also have a Mardi Gras Ball and have a court with a King and Queen and debutauntes and then everyone else is a guest of the ball....
http://www.mardigrasimports.com/
http://www.mardigrasoutlet.com/
http://www.kingcakeexpress.com/
http://www.mardigrasneworleans.com/