You could go as the Genie master and she your Dream of Jeanie harem girl.

I always go as a belly dancer because I love those outfits, lots of flowing veils and sexy looks from beneath them  Very sexy and your ATF will look great gyrating on the dance floor!

a married couple attended: he wore a 'standard' striped prisoner outfit, handcuffed and leg cuffed. SHE wore heels, skin tight black leather pants, a blue silk police shirt with the top buttons open over a black push-up bra, and carried a dildo blackjack. (she's about 34C-26-34, by the way) every other guy at the party spent the entire night pretending (to his own date) that he did not notice her. it was a riot.

he's a good friend of mine. he told me that they went home at about 2am and had sex for about 6 hours; showered, went out to breakfast, then came home and went back to bed til about 7pm. he said it was the best sex he ever had, and that they made a deal that she would take him prisoner again on his birthday

How about an Electrical Plug and Wall Outlet

Seems appropriate.  She should go as the plug.

Go as her pimp; have her in "street" clothes.

Want to hide something?

Put it in plain sight.