would it be like:

private server, you and a friend
set a password or kick people that come in
fight 200+ games a day

?? can someone explain please

yes that it is.
As you know, Qi is the games played and will reflect what belt are you.
Sometimes you dont need a friend to do Qi farming. You can have it by your own. Open two toribash apps and log in two or even just one account and start playing.
By that, you earn Qi and you'll be at any belt in no time.
-----
You can also do it in public servers.

is that against the rules?

yes its against the rules.

YES it is VERY bad and punishable by DEATH.

JK, you can get banned forever (a long time).

so you can get banned for playing with a friend if you fight 100+ times?

I don't think you will get banned for playing with a friend over 100+ times.
If you guys are REALLY addicted and have no life, I don't think that's a bad thing.

How do the mods and admins find out that you are qi farming though?

I think it only happens if you use multiple accounts.

Fighting 200 games with a friend over and over is not against the rules.

But, If you are purpousfully making those matches extremely fast such as telling your friend to automatically, dq, then yes, that would be qi farming and is a bannable offense.

How bout this ?
You have two account and Two version of Toribash (3.9 & 3.91 in this case)
You log your first account on Toribash 3.9
You log your second account on Toribash 3.91
Both Id Play in one Room
Then you're Farming