It would be just like Vulture-aid, it would be cheaper because you don't get money and ammo. So there's a Disco ball on the perk logo, the more consecutive kills you get, the brighter it flashes an faster it spins. Eventually disco music will start playing and the zombies will dance for a little bit and buy you some time, however. The time will drain faster if you shoot other than a Pack-a-punched weapon or a Ray-gun because those would blend in with the music. The Disco music would also go when one of your weapons runs out of ammo.
Oh... and disco light reflections will flash all around the player's vicinity, and perhaps the Mystery box could play some cool Disco music of it's own when the player gets inside.