too many fandoms
Three fandoms in one costume: wizard hat and cloak (Lord of the Rings); suspenders & bow-tie (Doctor Who); and a lightsaber (Star Wars) on top of a sonic screwdriver.
Good grief... this costume made my head hurt...
UPDATE: This photo was featured in an on-line article on Neatorama "The 12 Best Geeky Costumes for Halloween 2012". The author chose three of my mash-up pics which greatly amused me! :-D