We have family trees. It's nothing more than the chain of big-little brothers (my big brother's big brother is in my family tree because I was chosen by his little. No fancy initiation or anything).
We jokingly have friendly rivalries between trees, but at the end of the day, we're all brothers.
If it's not a national thing, I agree with Kevin -- make stuff up as you go along.
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*does side bends and sit-ups*
*doesn't lose butt*
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