What you'll need:
Short-sleeved white button-up shirt
Necktie (preferably black, no more than moderately fashionable)
Book of Mormon
Slacks and dress shoes
Bike helmet and suspenders (optional)
Between the hit Broadway musical and 2012 GOP candidates, Mitt Romney and Jon Huntsman, Mormons have a big year. Dressing as a Mormon missionary is a great way to tap into the phenom, and is an especially easy costume to prep. Just grab some business-casual clothes, slap on a name tag with the appropriate denomination (the Church of Jesus Christ of Latter-day Saints) and look abstemious. If you're feeling really ambitious, you can try to convert your fellow revelers. Or you might carry some engraved golden plates, as a nod to the tablets Joseph Smith said an angel gave him when he established the religion circa 1830. But be wary: if you're planning on partaking of the devil's brew, you best do it on the sly.