Halloween Costumes

One of my officemates was is looking for paired Halloween costumes for her and her hubbie. Her are the suggestions my office came up with:

Pirates
An electron and a proton
The Curies
Romeo and Juliet
Ghosts
The ghosts of Romeo and Juliet
Each other (dismissed because it would probably end in divorce)
Liu Bui and Guan Yu
An obelisk and an ape
A ying and a yang
Thing 1 and Thing 2