One element familiar to carnival and fair-goers alike is one of those colorful Tyvek wristbands. If you're going for a carnival-themed wedding, giving guests wristbands could totally help set the mood. They fit in perfectly at Jenn and Cody's colorful, circus-y wedding.
Wristbands are great for keeping track of those who are of legal age to drink, or to get into certain areas of a shared-space venue. And since most of them come with a unique number on each, you could use them for raffles or giveaways.