You could go as...
Cousin Oliver from The Brady Bunch
Cousin Skeeter
The Joker being Borat
Liam Gallagher's Penis
Casey Anthony's Dad
Antoine Dodson's sister
Angela Bassett
Bloody show
Samantha from SATC2's bleached butthole
A pack of Rolos (everybody loves Rolos)
Kevin Sorbo (from the last season of The OC, not Hercules)
Doug Funny as a Nazi
Sexy Internet Predator
A balloon!