Each year you get a chance to sing FIVE moderately difficult barbershop arrangements with other like-minded people who are 100% confident on their notes and words.
(If they aren't they often still come and cheer from the crowd.)

During the Harmony Platoon you are thrown into random pick up quartets where you get a very short amount of time to rehearse and perhaps add a little smile and sparkle to your upcoming performance.

Then you come back together and your quartet performs one of the songs randomly drawn from a hat and all your new and long-time friends cheer wildly as you try to out-remember the words.