Want to get an early jump on your offensive, topical Halloween costume for the year?

When everyone else dresses up as a zombie AMY WINEHOUSE or bullet-ridden OSAMA BIN LADEN, you'll be the only jerk at the party wearing THIS CASEY ANTHONY mask.

The mask showed up on eBay with the headline "Casey Anthony latex rubber mask, [extremely] rare."  The description says that only nine of these masks were made.

The auction ends today at 9:00 P.M. Eastern.  And if you want the mask it's going to cost you . . . it's already over $20,000.

(eBay)