Wad.
This is my favorite way to divide a group into smaller groups. Learned it working at summer camps, still use it today when I facilitate programs for college students and other adult groups. Just about every time it creates a 50/50 split, +/- a couple people. Kids cheat because they want to be with their buddies, adults start trash talking and get defensive when they're asked to switch for the sake of even numbers. Best done with no explanation, just a simple "wadders over here, folders over there".