Duo Halloween Costume: Brennan and Dale From "Step Brothers" Pay homage to Will Ferrell and John C. Reilly's characters from the 2008 comedy "Step Brothers" with this two-person Halloween costume. Make sure you tell all your fellow partygoers that you sleep in bunk beds because it offers more room for activities. What to wear for Brennan: Find an obscure pop culture t-shirt in a vintage shop. Grab some plaid shorts, and rub dirt all over yourself. What to wear for Dale: A homemade Spring Break '84 shirt and green shorts that are way too small for you. Get dirty and maybe even grab a shovel. Image Source: Everett Collection