Never accept this challenge. The cinnamon challenge is a classic prank for a game of truth or dare, or it can just be fun to watch others attempt it. The point if the challenge is to swallow a spoonful of cinnamon, which is near impossible. The cinnamon quickly dries up your mouth, and you will quickly choke if you attempt to breath out of your mouth or talk.
Friend: *takes out cinnamon and a spoon* "cinnamon challenge!"