Octomom -- Permission to FIGHT During Rehab

Nadya Suleman has been granted permission to yell and scream at random strangers during her stint in rehab ... in fact, she's even getting paid for it ... TMZ has learned.

As we previously reported, Octo is making serious money as a featured arguer on a debate website called Deeyoon.com -- where people (like Michael Lohan) often go to war with Nadya over explosive issues like child care.

So when Nadya decided to check herself into rehab for a Xanax addiction this weekend, she made it clear to the center that she couldn't go 30 days without a paycheck ... and got permission to work from the facility.

In fact, we're told the center has agreed to design Nadya's treatment schedule around her work schedule ... which consists of several 90 minute video chat sessions from a computer at the facility.