Other costumes that are P.C. offensive:
ghost/Klansman
Nazi
Native American
Mexican bandito
Furry
Ninja (offensive to Orientals)
Pirate (offensive to Somalis)
Witch/Wiccan
Zombies (offensive to the voting dead)
Any copyright protected character
Anything not on this list needs pre-approval.
Approved for use: George W. Bush mask, but not Obama.