1. Eat large amounts of food at annual gatherings.
2. Play made-up games together.
3. Make music together.
4. Discuss Obamacare.
5. Watch exciting movies together.
6. Easy messy food together (without judgment).
7. Have inside jokes.
8. Have their own special language.
9. Know their members at their worst, and still love them.
10. Know their members at their best, and love them all the more.