Duo Halloween Costume: Leonard and Sheldon From "The Big Bang Theory" Calling all fans of "The Big Bang Theory". This easy two-person Halloween costume has your name written all over it. What to wear for Leonard: Black Converse trainers, jeans, a graphic t-shirt, and a jacket with a hood. Don't forget your thick glasses. What to wear for Sheldon: Brown trousers that are a little too short, and layer a long-sleeved t-shirt over a short-sleeved one with something geeky on it. Image Source: CBS